The focus in computer-aided design is shifting from geometric aspects to functional aspects and from the detail design to a multi-aspect conceptual design. As a consequence, new concepts are emerging and being tested, for instance, for comprehensive geometric and functional modeling in conceptual design. This paper introduces a new approach, which has been called relations-based design. Relations are existential, manifestation and behavioral associations, dependencies and interactions between human, artifacts and environments. Nucleus is introduced as a generic modeling entity, which includes two regions of one or two objects that are interconnected by a system of relations in a particular situation. A design concept (or an artifact) is conceived as a purposeful composition of specific instances of nuclei. The nucleus can be instantiated at multiple levels such as entity, component, subassembly and assembly. A set of relations has been predefined to express qualitative and quantitative associations, dependencies and interactions between objects in a parameterized form on these levels. As a modeling entity, the nucleus offers many advantages in multi-aspect conceptual modeling by integrating incomplete and uncertain geometric, structural, physical and behavioral modeling. The paper introduces the foundational theories, the most important mathematical definitions, and the concept of information management. Finally, it points at some advantages of relations based modeling in the context of application cases comparing it with the physical modeling offered in a commercial system.
A theoretical framework for the net land-to-atmosphere CO<sub>2</sub> flux and its implications in the definition of "emissions from land-use change"
