As consumers demand diverse values reflecting their individual needs and wants from various viewpoints, including economical, ecological and experiential concerns, more comprehensive and more flexible ways to provide values to consumers are desired. Product-Service Systems (PSS) have been proposed as a solution to realize such diverse value provision. In this paper, a systematic methodology for designing PSS based on activities and functions is proposed, which is much different from the case of product design. The proposed PSS design process includes the following six steps: requirement identification and value proposition, stakeholder activity design, PSS functional modeling, function-activity mapping and PSS concept generation, PSS concept detailing and PSS concept prototyping. In the proposed PSS design process, the activities of stakeholders are defined and analyzed via service blueprint. The functions of PSS fulfilling target values are then defined and represented with the specification service providers and service receivers, and they are further decomposed into sub-functions. Then the relationship between stakeholder activities and functions are established by considering associated stakeholders, and the PSS concepts are generated by mapping product and service elements. Sample case studies are conducted to validate the proposed PSS design process.

In this paper, a published ontology of engineering design activities is modeled and analyzed using the design structure matrix (DSM). Specifically, the ontology analyzed in this research provides a basis for describing engineering design activities and subsequently design processes in an unambiguous manner. However, the proposed ontology lacks a computational representation and the information flow between activities is not adequately described. Thus, complex design processes cannot be represented using the ontology. The design activity ontology is modeled and analyzed using the DSM. First, the information flows between design activities are identified and their inter-relationships are described. Four different cases for representing the flow of information between design activities are modeled. In Case 1 and 2 feedback between information output and information input within an activity is captured. Whereas, in Case 3 and 4 it is assumed that no feedback between output and input exists within an activity. DSM analyses, including partitioning and tearing, are performed on the model. Observations and conclusions drawn from these analyses include the further decomposition of design activities, grouping of design activities, and lack of information flow between seemingly related activities. Based on these observations, recommendations are made to refine the ontology. Finally, additional research is required for developing a computational ontology of design activities.