David T. McWherter

Database techniques for archival of solid models

This paper presents techniques for managing solid models in modern relational database management systems. Our goal is to enable support for traditional database operations (sorting, distance metrics, range queries, nearest neighbors, etc) on large databases of solid models. As part of this research, we have developed a number of novel storage and retrieval strategies that extend the state-of-the-art in database research as well as change the way in which solid modeling software developers and design and manufacturing enterprises view CAD-centric data management problems. Past research and current commercial systems for engineering information management and Product Data Management (PDM) have predominantly taken annotation and document-based approaches—where the solid modeling data itself is simply stored as a related file to other project documents. Research in CAD and engineering databases has produced great advances, such as representation schemas for STEP-based data elements, however existing technologies stop short of enabling content-based and semantic retrieval of solid modeling data of the types now available for other higher-dimensional media (images, audio and video). Our approach encodes solid model BRep information as a Model Signature Graph. We demonstrate how Model Signature Graphs can be used for topological similarity assessment of solid models and enable clustering for data mining of a large design repositories. We believe this work will begin to bridge the solid modeling and database communities, enabling new paradigms for interrogation of CAD datasets.

Solid Model Databases: Techniques and Empirical Results

This paper presents techniques for managing solid models in relational database agement systems. Our goal is to enable support for traditional database operations ing, distance metrics, range queries, nearest neighbors, etc) on large databases o models. We introduce an approach to compare models based on shape using inform extracted from the model boundary representation into Model Signature Graphs. We how the Model Signature Graphs can be used to compute topological distances a models and how to use these measures to create metric spaces for indexing and clu of solid models. We believe this work will begin to bridge the solid modeling and data communities, enabling new paradigms for interrogation of CAD datasets based o engineering content of solid models. @DOI: 10.1115/1.1430233 #

Building an IP network quality-of-service testbed

The Drexel Network Toolkit is a software package for testing various approaches to QoS on IP-based networks. It uses Linux and DiffServ packet-marking primitives to classify and prioritize packets. DNT was used in a project to evaluate satellite based IP delivery for multimedia applications in telemedicine and telemaintenance.