18630917
Multimedia documents with elastic time
Time is an essential component in interactive multimedia documents (or systems). We present the elastic time model for multimedia documents. Using the metaphor of a spring system, it allows authors to associate with each multimedia object a minimum and a maximum length and a length at rest. Authors can connect the (elastic) objects by de ning temporal relationships among them. If the given specication is consistent, a document is produced which is also elastic, with a minimum, a maximum, and an optimal length. As such, our elastic model associates with a document a range of feasible solutions in addition to an optimal one. The author can then select from the acceptable range an alternative length for the document, and the system will compute a revised solution that takes the additional global constraint into e ect. The system can answer questions, such as: \Can I show this multimedia presentation in 10 minutes? If so, how should all the objects be scheduled?" Furthermore, the system also takes fairness into consideration and distributes any necessary stretching or shrinking across multimedia objects contained in a document. As such, the elastic time model provides expressive power and exibility in document auThe author's current address is: University of Maryland, College Park, MD 20742, JUNESONG @ CS.UMD.EDU thoring and browsing. The proposed approach has been implemented in Smalltalk/OS2.
20698705
Home health care support
We describe an ap@ication to interconnect health care providers and thew patients in the home. The application includes information services, symptom analy SIS, ~idance in the performance of procedures, emotmnal support, and communications among the health care providers, patients and caretakers.
6041360
Modeling timed user-interactions in multimedia documents
Interactive multimedia documents (or systems) can be characterized by active user participation and the diversity of multimedia information accessed at various levels of granularity. They need to support extensive user participation in selecting and tailoring the information and its presentation. Multimedia information fragments may vary from portions of video, pieces of audio, newspaper quotations or chapters of a book. Effectively managing the creation, evolution and complexity of multimedia documents formed by combining media fragments is an essential capability. We consider the hyperstory model of a multimedia document, where a document is structured hierarchically in three dimensions: time, space and asynchrony. The model provides a layered approach in structuring multimedia documents, thus reducing the complexities of large systems. The hyperstory model supports user interactions that are timed, and also supports preemptive resuming. Timed user interactions with the document are modeled with a newly introduced timed Petri-net (TPN*). TPN* is used to infer the behavior of the system. This paper describes TPN*'s modeling and analysis and its application to the hyperstory model.
528361
Eliminating Bottlenecks in Overlay Multicast
Recently many overlay multicast systems have been proposed due to the limited availability of IP multicast. Because they perform multicast forwarding without support from routers, data may be delivered multiple times over the same physical link, causing a bottleneck. This problem is more serious for applications demanding high bandwidth such as multimedia distribution. Although such bottlenecks can be removed by changing overlay topology, a naive approach may create bottlenecks in other parts of the network. In this paper, We propose an algorithm that removes all bottlenecks caused by the redundant data delivery of overlay multicast, detecting such bottlenecks using a wavelet-based technique we recently proposed. In a case where the source rate is constant and the available bandwidth of each link is not less than the source rate, our algorithm guarantees that every node receives at the full source rate. Simulation results show that even in a network with a dense receiver population, our algorithm finds a tree that satisfies all the receiving nodes while other heuristic-based approaches often fail.
1783266
Robustness in large-scale random networks
We consider the issue of protection in very large networks displaying randomness in topology. We employ random graph models to describe such networks, and obtain probabilistic bounds on several parameters related to reliability. In particular, we take the case of random regular networks for simplicity and consider the length of primary and backup paths in terms of the number of hops. First, for a randomly picked pair of nodes, we derive a lower bound on the average distance between the pair and discuss the tightness of the bound. In addition, noting that primary and protection paths form cycles, we obtain a lower bound on the average length of the shortest cycle around the pair. Finally, we show that the protected connections of a given maximum finite length are rare. We then generalize our network model so that different degrees are allowed according to some arbitrary distribution, and show that the second moment of degree over the first moment is an important shorthand for behavior of a network. Notably, we show that most of the results in regular networks carry over with minor modifications, which significantly broadens the scope of networks to which our approach applies. We present as an example the case of networks with a power-law degree distribution.
1994375
Effective Temporal Aggregation Using Point-Based Trees
Temporal databases introduce the concept of time into underlying data, and provide built-in facilities that allow users to store and retrieve time-varying data. The aggregation in temporal databases, that is, temporal aggregation is an extension of conventional aggregation on the domain and range of aggregates to include time concept. Temporal aggregation is important for various applications, but is very expensive. In this paper, we propose a new tree structure for temporal aggregation, called PA-tree, and aggregate processing method based on the PA-tree. We show that the time complexity of the proposed method is better than those of the existing methods. The time complexity of the proposed method is shown to be indeed the lower bound of the problem. We perform comparative experiments and show the performance advantage of our proposed method in practice.
46306635
A Blind Watermarking for 3-D Dynamic Mesh Model Using Distribution of Temporal Wavelet Coefficients
In this paper, we present a watermarking method for 3-D mesh sequences with a fixed connectivity. The main idea is to transform each coordinate of vertex with the identical connectivity index along temporal axis using wavelet transform and modify the distribution of wavelet coefficients in temporally high (or middle)-frequency frames according to watermark bit to be embedded. Due to the use of the distribution, our method can retrieve the hidden watermark without any information about original mesh sequences in the process of watermark detection. To increase the watermark capacity, all vertices are divided into groups, namely bins, using the distribution of scaling coefficients in low-frequency frames. As the vertices with the identical connectivity index over whole frames belong to one bin, their wavelet coefficients are also assigned into the same bin. Then, the watermark is embedded into each axis of the wavelet coefficients. Through simulations we show that the proposed is fairly robust against various attacks that are probably concerned in copyright protection of 3-D mesh sequences.
14547237
Foundations for the Run-Time Monitoring of Reactive Systems - Fundamentals of the MaC Language
As the complexity of systems grows, the correctness of systems becomes harder to achieve. This difficulty promotes a run-time monitoring technique as a promising complementary methodology for higher system assurance. To formalize and understand the computational nature of run-time monitoring is a key to utilize this valuable technique. In this paper, we formalize the notion of run-time monitoring of reactive systems in terms of ω-languages and show that the language of Monitoring and Checking (MaC) architecture, called MEDL, is expressive enough for the run-time monitoring. 
 
First, we provide a descriptive theory for the class of monitorable languages and show that this class of languages coincides with the class Π01 of the Arithmetic hierarchy. Second, we introduce a class of automata with storage that can be used to describe the class of monitorable languages using connections to the Arithmetic hierarchy. Finally, we show that MEDL can express the class of monitorable languages via the correspondence between MEDL and the automata with storage.