27040625
Repository replication using SMTP and NNTP
We describe our progress on NSF ISS 0455997, "Shared Infrastructure Preservation Models". The focus of our efforts is to evaluate different preservation models based on Internet infrastructure that sites already have. Specifically, we investigate replicating the contents of a repository using the Simple Mail Transport Protocol ("email") and the Network News Transfer Protocol ("news").
7794743
Efficient, automatic web resource harvesting
There are two problems associated with conventional web crawling techniques: a crawler cannot know if all resources at a non-trivial web site have been discovered and crawled ("the counting problem") and the human-readable format of the resources are not always suitable for machine processing ("the representation problem"). We introduce an approach that solves these two problems by implementing support for both the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) and MPEG-21 Digital Item Declaration Language (DIDL) into the web server itself. We present the Apache module "mod_oai", which can be used to address the counting problem by listing all valid URIs at a web server and efficiently discovering updates and additions on subsequent crawls. Our experiments indicated comparable performance for initial crawls, and dramatic increases in update speed mod_oaican also be used to address the representation problem by providing "preservation ready" versions of web resources aggregated with their respective forensic metadata in MPEG-21 DIDL format.
7878072
Imperceptible Sensory Channels
System designers can use imperceptible sensory channels to create smarter, safer, and more secure environments. Beyond their diverse applications, imperceptible sensory channels suggest a new approach to the problem of machine perception. In adapting a video camera a device designed to capture human-readable images for use by the PDP-6, Minsky and Papert had to match perceptual algorithms to the sensor's capabilities. In contrast, for sensory channels such as electric field imaging that have no human analog, the sensor hardware can be designed to support perceptual algorithms.
45241521
Association Schemes, Superschemes, and Relations Invariant Under Permutation Groups
Abstract An association scheme is the associated scheme of a superscheme iff it is a permutation group scheme. The group and its action are recovered from the Bose-Mesner superalgebra of the superscheme, which is a 'quantised' version of a Krasner (relation) algebra of the second kind.
17602182
Architecture of the artifact-based collaboration system matrix
The UNC Collaboratory project is concerned with both the process of collaboration and with computer systems to support that process. Here, we describe a component of the Artifact-Based Collaboration (ABC) system, called the Matrix, that provides an infrastructure in which existing single-user applications can be incorporated with few, if any, changes and used collaboratively. We take the position that what is needed is not new tools but better infrastructure for using familiar single-user tools collectively. The paper discusses the Matrix architecture, a Virtual Screen component, and generic functions that provide conferencing, hyperlinking, and recording of users' actions for all applications. INTRODUCTION AND MOTIVATION
5097884
Columbia Digital News System. An environment for briefing and search over multimedia information
In this paper we describe an ongoing research project called the Columbia Digital News System. The goal of this project is to develop a suite of effective interoperable tools with which people can find relevant information (text, images, video, and structured documents) from distributed sources and track it over a period of time. Our initial focus is on the development of a system with which researchers, journalists, and students can keep track of current news events in specific areas.
16182080
Self adaptation of mutation rates in a steady state genetic algorithm
This paper investigates the use of genetically encoded mutation rates within a "steady state" genetic algorithm in order to provide a self-adapting mutation mechanism for incremental evolution. One of the outcomes of this work will be a reduction in the number of parameters required to be set by the operator, thus facilitating the transfer of evolutionary computing techniques into an industrial setting. The NK family of landscapes is used to provide a variety of different problems with known statistical features in order to examine the effects of changing various parameters on the performance of the search. A number of policies are considered for the replacement of members of the population with newly created individuals and recombination of material between parents, and a number of methods of encoding for mutation rate are investigated. Empirical comparisons (using the "best-of current-population" metric) over a range of test problems show that a genetic algorithm incorporating the best "flavour" of the adaptive mutation operator outperformed the same algorithm when using any one of a variety of "standard" fixed mutation rates suggested by other authors.