Stephen Abrams

Efficient and reliable methods for rounded-interval arithmetic

We present an efficient and reliable method for computing the unit-in-the-last-place (ulp) of a double-precision floating-point number, taking advantage of the standard binary representation for floatingpoint numbers defined by IEEE Std 754-1985. The ulp is necessary to perform software rounding for robust rounded-interval arithmetic (RIA) operations. Hardware rounding, using two of the standard rounding modes defined by IEEE-754, may be more efficient. RIA has been used to produce robust software systems for the solution of systems of nonlinear equations, interrogation of geometric and differential properties of curves and surfaces, curve and surface intersections, and solid modeling.

The digital ocean

The ocean, is fundamentally important to many areas of modern society and thus improved knowledge of the ocean is essential. Ocean scientists have made remarkable progress in observation technology, modeling and assimilation in physical oceanography, acoustics, and biology. To some extent, such advances have been confined to each discipline. Therefore a great demand has arisen for a modern distributed computing and networking infrastructure within which we bring together advanced modeling, observation tools and field estimation methods. The paper describes a knowledge network of distributed heterogeneous data and software resources for multidisciplinary ocean research.

The role of format in digital preservation

The concept of representation format permeates all technical aspects of digital repository architecture and is, therefore, the foundation of many, if not all, digital preservation activities. Digital formats need to be understood both as general classes of encodings and in the specific instances of digital objects. The Digital Library Foundation (DLF) has sponsored an initial investigation into the creation of a global digital format registry (GDRF) to maintain format representation information. Using such information, ancillary tools and services can be created for additional repository and preservation‐related functions such as format‐specific object identification, validation, and characterization. JSTOR and the Harvard University Library are cooperating on the development of an extensible format validation framework called JHOVE. This paper introduces both the GDFR and JHOVE projects.

XML for e‐journal archiving

e‐journals have many advantages over print, including enhanced media types, actionable reference links, and sophisticated searching capabilities. However, for many institutional subscribers, e‐journals are not an acceptable replacement for print without the reassurance that E‐journal content is maintained in a sustainable archival form for guaranteed future retrieval. Domain‐neutral schemas for e‐journal content defined in XML provide an appropriate mechanism for capturing e‐journal content in a manner that is amenable to long‐term preservation and retrieval. We present the results of a study of this problem undertaken by the Harvard University Library as part of the Andrew W. Mellon Foundation’s E‐journal Archiving Project. One tangible result of this project has been the development of an XML e‐journal article‐level archival interchange DTD.

Distributed Information and Computation in Scientific and Engineering Environments

The NSF Invitational Workshop on Distributed Information, Computation, and Process Management for Scientific and Engineering Environments (DICPM) brought together domain specialists from engineering and the ocean, atmospheric, and space sciences involved in the development and use of simulations of complex systems, and computer scientists working on distributed repositories, visualization, and resource management. The objective was to formulate directions for research efforts to facilitate effective collaboration and to help increase access to information and sharing of results and tools useful in large-scale, distributed, multidisciplinary scientific and engineering environments. Three broad problem areas inhibit such activities: (1) Computational, e.g, insufficient infrastructure for the sharing of very large amounts of information, results, and tools; (2) Structural institutional barriers, e.g., funding, publication, and promotion policies; and (3) Social, e.g., communication barriers stemming from narrow specialization. The participants supported specific steps to address these problems: explicit support and incentives for multidisciplinary activities; the development of digitial libraries to enhance interdisciplinary communication and understanding; and development of a “virtual scientific marketplace” to disseminate tools, results, and expertise;