2,522 research outputs found
Time Dependency in Diffusion Models: Gamma-Diffusion Models as an Alternative to the Hernes Model
Design Patterns for Description-Driven Systems
In data modelling, product information has most often been handled separately
from process information. The integration of product and process models in a
unified data model could provide the means by which information could be shared
across an enterprise throughout the system lifecycle from design through to
production. Recently attempts have been made to integrate these two separate
views of systems through identifying common data models. This paper relates
description-driven systems to multi-layer architectures and reveals where
existing design patterns facilitate the integration of product and process
models and where patterns are missing or where existing patterns require
enrichment for this integration. It reports on the construction of a so-called
description-driven system which integrates Product Data Management (PDM) and
Workflow Management (WfM) data models through a common meta-model.Comment: 14 pages, 13 figures. Presented at the 3rd Enterprise Distributed
Object Computing EDOC'99 conference. Mannheim, Germany. September 199
The Reification of Patterns in the Design of Description-Driven Systems
To address the issues of reusability and evolvability in designing self-
describing systems, this paper proposes a pattern-based, object-oriented,
description-driven system architecture. The proposed architecture embodies four
pillars - first, the adoption of a multi-layered meta-modeling architecture and
reflective meta-level architecture, second, the identification of four data
modeling relationships that must be made explicit such that they can be
examined and modified dynamically, third, the identification of five design
patterns which have emerged from practice and have proved essential in
providing reusable building blocks for data management, and fourth, the
encoding of the structural properties of the five design patterns by means of
one pattern, the Graph pattern. The CRISTAL research project served as the
basis onto which the pattern-based meta-object approach has been applied. The
proposed architecture allows the realization of reusability and adaptability,
and is fundamental in the specification of self-describing data management
components.Comment: 10 pages 11 figure
Meta-Data Objects as the Basis for System Evolution
One of the main factors driving object-oriented software development in the Web- age is the need for systems to evolve as user requirements change. A crucial factor in the creation of adaptable systems dealing with changing requirements is the suitability of the underlying technology in allowing the evolution of the system. A reflective system utilizes an open architecture where implicit system aspects are reified to become explicit first-class (meta-data) objects. These implicit system aspects are often fundamental structures which are inaccessible and immutable, and their reification as meta-data objects can serve as the basis for changes and extensions to the system, making it self- describing. To address the evolvability issue, this paper proposes a reflective architecture based on two orthogonal abstractions - model abstraction and information abstraction. In this architecture the modeling abstractions allow for the separation of the description meta-data from the system aspects they represent so that they can be managed and versioned independently, asynchronously and explicitly. A practical example of this philosophy, the CRISTAL project, is used to demonstrate the use of meta-data objects to handle system evolution
From Design to Production Control Through the Integration of Engineering Data Management and Workflow Management Systems
At a time when many companies are under pressure to reduce "times-to-market"
the management of product information from the early stages of design through
assembly to manufacture and production has become increasingly important.
Similarly in the construction of high energy physics devices the collection of
(often evolving) engineering data is central to the subsequent physics
analysis. Traditionally in industry design engineers have employed Engineering
Data Management Systems (also called Product Data Management Systems) to
coordinate and control access to documented versions of product designs.
However, these systems provide control only at the collaborative design level
and are seldom used beyond design. Workflow management systems, on the other
hand, are employed in industry to coordinate and support the more complex and
repeatable work processes of the production environment. Commercial workflow
products cannot support the highly dynamic activities found both in the design
stages of product development and in rapidly evolving workflow definitions. The
integration of Product Data Management with Workflow Management can provide
support for product development from initial CAD/CAM collaborative design
through to the support and optimisation of production workflow activities. This
paper investigates this integration and proposes a philosophy for the support
of product data throughout the full development and production lifecycle and
demonstrates its usefulness in the construction of CMS detectors.Comment: 18 pages, 13 figure
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