Marco Arguedas

Concept maps: integrating knowledge and information visualization

Information visualization has been a research topic for many years, leading to a mature field where guidelines and practices are well established. Knowledge visualization, in contrast, is a relatively new area of research that has received more attention recently due to the interest from the business community in Knowledge Management. In this paper we present the CmapTools software as an example of how concept maps, a knowledge visualization tool, can be combined with recent technology to provide integration between knowledge and information visualizations. We show how concept map-based knowledge models can be used to organize repositories of information in a way that makes them easily browsable, and how concept maps can improve searching algorithms for the Web. We also report on how information can be used to complement knowledge models and, based on the searching algorithms, improve the process of constructing concept maps.

Using WordNet for word sense disambiguation to support concept map construction

The construction of a concept map consists of enumerating a list of concepts and – a more difficult task – determining the linking phrases that should connect the concepts to form meaningful propositions. Appropriate word selection, both for concepts and linking phrases, is key for an accurate knowledge representation of the user’s understanding of the domain. We present an algorithm that uses WordNet to disambiguate the sense of a word from a concept map, using the map itself to provide its context. Results of preliminary experimental evaluations of the algorithm are presented. We propose to use the algorithm to (a) enhance the ”understanding” of the concept map by modules in the CmapTools software that aide the user during map construction, and (b) sort the meanings of a word selected from a concept map according to their relevance within the map when the user navigates through WordNet’s hierarchies searching for more appropriate terms.

An Adaptive and Efficient Peer-to-Peer Service-Oriented Architecture for MANET Environments with Agile Computing

Realizing adaptive and efficient peer-to-peer service-oriented architectures for MANET environments is a challenging problem. In particular, robust and efficient service discovery and service migration are critical in the constantly changing and bandwidth limited MANET environments. In these scenarios, service migration lays the foundation for self-adaptive architectures. This paper describes the agile computing approach to peer-to-peer service discovery and service migration and provides a performance evaluation of these functions in the context of the agile computing middleware. The experimental results presented in the paper show that applications built on top of the agile computing middleware are capable of opportunistically exploiting transient computing resources in the MANET environment.

Mockets: a comprehensive application-level communications library

Mockets is a comprehensive communications library designed to address challenges specific to mobile ad-hoc networks. Mockets have been implemented at the application-level to simplify deployment and portability. Both stream-oriented and message-oriented abstractions are supported, with the message-oriented service providing multiple classes of service (reliable, unreliable, sequenced, unsequenced), message tagging and replacement, and prioritization. Mockets also interfaces with a policy management infrastructure to support bandwidth limitation. Finally, mockets supports transparent migration of communication endpoints across hosts without the need to terminate and reestablish connections. Mockets provides similar semantics to TCP but performs better than TCP on ad-hoc networks

Resource and Service Discovery in Wireless AD-HOC Networks with Agile Computing

Resource and service discovery in tactical networking environments is a challenging problem. The ad-hoc and peer-to-peer nature of the network invalidates many traditional approaches to resource and service discovery that rely on registries. The agile computing middleware supports opportunistic service and resource discovery and tasking in tactical environments. The group manager component of the middleware supports bandwidth-efficient discovery of neighboring nodes, their resources (including CPU, memory, storage, and connectivity), and their services. Nodes may join one or more groups that allow resources and services to be categorized into related sets. Applications using the group manager are notified about the appearance and disappearance of peers as well as changes in memberships of groups. The group manager is efficient in finding neighboring services and is designed to improve the probability of finding resource-rich nodes. Cross-layer integration between the group manager and the MANET layer reduces the network overhead and improves performance.

A mobile agent-based communications middleware for data streaming in the battlefield

In this paper we introduce the FlexFeed framework in the context of military combat operations. FlexFeed realizes the notion of agile computing for data-streaming and implements a flexible, robust and efficient publish/subscribe infrastructure for dynamic ad hoc environments under resource and policy constraints. The framework uses mobile software agents for underlying configuration and policy enforcement. The paper illustrates the effectiveness of the framework with quantitative experiments over simulated scenarios

A directed expansion topology control algorithm for mobile Ad-Hoc networks

In this paper we present the directed expansion algorithm, a distributed and proactive topology control algorithm used for increasing the coverage of mobile nodes over a geographical area while maintaining network connectivity. The proposed approach is fully distributed and assumes a free-space wireless propagation model and no-obstacle navigation field. The algorithm relies on a virtual network backbone, and assumes the existence of a distributed mechanism for computing the network backbone. The proposed algorithm also maintains a fully connected topology by making the expansion task aware of the location and extent of the network backbone. We describe the directed expansion algorithm in detail, and present simulation results and performance analysis. Our results show the effectiveness of the proposed approach in expanding coverage over a geographical area.

Investigating the Use of Topology Adaptation for Robust Multi-path Transport: A Preliminary Study

In this paper we introduce a topology control algorithm for increasing transport robustness and efficiency by creating two simultaneous communication paths between the source and destination nodes of a data flow. We make use of a cross-layer substrate that allows us to detect the flows of data in the network while also providing finer control of the routing. Because information of flow traffic in the network is available, the algorithm attempts to achieve intra-flow interference reduction by exploiting node mobility.

The mLab-PENGWUN hybrid emulation environment for airborne networks

In this paper we introduce a hybrid emulation infrastructure that combines theoretical path loss models with data-driven statistical link models. The goal is to provide a specialized emulation environment for the development and validation of airborne networking protocols, in support of the AFRLs PENGWUN research effort. After a brief discussion of our architecture design and policy enforcement mechanisms, we discuss our approach for data-driven link emulation for airborne networks.