Formal Requirements of a Simple Turbofan Using the SpeAR Framework

Traditional system engineering methods focus on sequential activities of requirements specification, design, implementation, integration, verification, and validation. Often times this process proceeds with requirements that are ill formed, underspecified, inconsistent, or simply do not capture the designer's intent. The inherent flaw in this approach is that any specification or design errors found in the verification phase require rework through all steps in the process, often resulting in substantial cost and schedule overruns. In this paper we introduce a formalized requirements development framework named Specification and Analysis of Requirements (SpeAR) that is designed to aid users in developing more consistent, well-formed requirements that mathematically capture the designer's intent while adhering to a natural language look and feel. Additionally, these formally constructed requirements enable early analysis; reducing errors, reducing cost. SpeAR provides a set of formal patterns that map to English grammar commonly used in expressing system requirements. This paper will discuss the features of SpeAR and briefly discuss how to apply the framework to a simple turbofan which was used to specify and analyze requirements.