Primary constraint implication

Figure 12.19 shows the implication of concentration taken as a primary constraints and time taken as a secondary constraints. The concentration scale represents the maximum inlet and outlet concentrations in the given processes. This concentration is increasing in the direction of the arrow on the scale. Processes A and D precede processes B and C, respectively. This implies that the secondary constraints (time) is satisfied in both case (i) and case (ii). Moreover, water from process A has concentration less than the maximum concentration allowed in process B. Therefore, in case (i) both the concentration and time constraints are met and water from process A can safely be reused in process B. However, water from process D has concentration higher than the maximum concentration allowed in process C, which implies that the primary constraints (concentration) is not met. Therefore, water from process D cannot be reused in process C, although the secondary constraints (time) is met. 

Fig. 12.19 Implication of concentration taken as a primary constraints (Majozi et al., 2006)...

The primary measure of success of a software system, and by implication its quality, is the degree to which it meets its requirements. RE therefore plays a pivotal role in determining the quality of a software system and its fitness for purpose. It lies at the heart of software development projects, since the outcomes of an RE process provide cmcial inputs into project planning, technical design, and evaluation. Of course, RE is not an activity that only takes place at the start of a software development project only. The discovery of requirements often continues well into the development process, and can be influenced by the presence of existing technical solutions and constraints. Broadly speaking, however, RE is a front-end development activity—determining subsequent development decisions and used as a measure of success for the final software system that is delivered. 

---