Modeling Languages: Declarative and Imperative Descriptions of Chemical Reactions and Processing Systems

This chapter describes two modeling languages: Language for Chemical Reasoning (LCR) and MODELing LAnguage (MODEL.LA.). Both are based on the same principles and have a common structure. The chapter describes the components of a modeling language, called LCR that was developed to represent the knowledge about chemically reacting systems. First, the basic modeling elements that constitute the building blocks for the representation of the declarative knowledge about molecules, reactions, and pathways have been described. Second, the semantic relationships among the basic modeling elements have been discussed. These semantic relationships establish the “meaning” behind the linguistic expressions, defining knowledge about molecules and reactions. Third, the syntax used by the language for the description of chemically reacting systems has been presented. The nine basic modeling elements of LCR are generic enough to allow (1) infinite extensibility of LCR's vocabulary through a finite set of rules, and (2) representation and analysis of any potential reaction pathway. The chapter also examines the mechanisms that LCR possesses to achieve these objectives. MODEL.LA. is a high-level, special-purpose language that was developed to support the modeling activities of a broad range of process engineering tasks; process design, simulation, operations planning, diagnosis, configuration of control systems, and others. MODEL.LA. is quite distinct in both scope and capabilities from other modeling languages such as Advanced System for Computations in ENgineering Design (ASCEND), MODeling Assistant (MODASS), and Object-oriented Modeling Language (OMOLA). MODEL.LA. shares many common features with LCR. Both languages share a common set of semantic relationships and a common syntax. They differ in their modeling elements that reflect the different vocabularies of chemistry and process engineering. The modeling elements of each language are organized into subsets, which depict the structural and behavioral knowledge of the corresponding domains. The chapter provides an overview of MODEL.LA.'s structure and discusses the utilization of MODEL.LA. within the scope of engineering problems.