This study seeks an affirmative answer to the question whether a knowledge-based approach to system of systems interoperation using semantic web standards and technologies can provide the centralized control of the capability for exchanging data and services lacking in a federation of systems. Given the need to collect and share real-time information and capitalize on globalization, organizations increasingly rely on interconnected system of systems capable of delivering unique capabilities not found in single systems. A central concern in system of systems engineering is the issue of coordination and interoperability between these interconnected systems. Special attention has to be given to interoperability with respect to federations of systems, which are coalitions of partner systems with decentralized power and authority. A major challenge in these systems' families is how to enable large-scale data and service interoperability without centralized management of the system of systems engineering activities. More complex technologies are necessary to automate the task of discovering capabilities matching requirements of the system of systems constituents (self-configuration). There is also a need to overcome conceptual barriers which obstruct the sharing of information among constituents and prevent them from exchanging services. This dissertation demonstrates that it is possible, by means of a knowledge-based approach using emerging semantic web technology, to enable the partial or full automation of the capability discovery, selection, and composition processes among constituent systems, and to resolve the conceptual differences of the information they exchange. Conceptual differences refer to differences in the syntactical structure and meaning of the information. This study describes a semantic mediation modeling approach that was developed based upon the state of practice in the fields of Semantic Web, Semantic Interoperability, and Semantically-Enabled Service Oriented Architectures. Furthermore, to add credibility to this approach, to illustrate characteristics of the approach, and to provide a clear description of the tasks involved in the modeling process, we present a prototype implementation that is based on realistic scenarios from existing context-aware ubiquitous (UbiComp) system architectures. Systems engineers may employ the approach to manage semantic knowledge of their system domain, expose that knowledge to a federation of interoperable systems, and discover and utilize information and functionality through the semantic knowledge exposed by other constituent systems of the federation. The study presents examples of semantic modeling products developed by applying the approach to a system of context-aware ubiquitous systems scenario; reviews useful findings; and provides recommendations for further research. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]