When Decomposition Increases Complexity: How Decomposing Introduces New Information Into the Problem Space

Decomposition is a dominant design strategy because it enables complex problems to be broken up into more manageable modules. However, although it is well known that complex systems are rarely fully decomposable, much of the decomposition literature is framed around reordering or clustering processes that optimize an objective function to yield a module assignment. As illustrated in this study, these approaches overlook the fact that decoupling partially decomposeable modules can require significant additional design work, with associated consequences that introduce considerable information to the design space. This paper draws on detailed empirical evidence from a NASA space robotics field experiment to elaborate mechanisms through which the processes of decomposing can add information and associated descriptive complexity to the problem space. Contrary to widely held expectations, we show that complexity can increase substantially when natural system modules are fully decoupled from one another to support parallel design. We explain this phenomenon through two mechanisms: interface creation and functional allocation. These findings have implications for the ongoing discussion of optimal module identification as part of the decomposition process. We contend that the sometimes-significant costs of later stages of design decomposition are not adequately considered in existing methods. With this work we lay a foundation for valuing these performance, schedule and complexity costs earlier in the decomposition process.

Development of a Design Procedure for Class E Amplifiers

Here, the step-by-step design procedure for a Class E amplifier is presented. An existing Class E amplifier system is described using a systems architecture approach. The design decomposition for the case study is written so that Physical Solutions (PSs; equivalent to Design Parameters) are in terms of component parameters (such as frequency or capacitance). Coupling issues are found to arise given constraints on transistor use. The design decomposition is altered to reflect the case where an amplifier is required to power a specific load. A discussion of transistor failure enables a design procedure to be developed by observing path-dependent coupling. The design procedure is tested through the design of a real amplifier. The designed amplifier is built and its performance measured.

Extension of Manufacturing System Design Decomposition to Implement Manufacturing Systems That are Sustainable

This paper offers an extension of axiomatic design theory to ensure that leaders, managers, and engineers can sustain manufacturing systems throughout the product lifecycle. The paper has three objectives: to provide a methodology for designing and implementing manufacturing systems to be sustainable in the context of the enterprise, to define the use of performance metrics and investment criteria that sustain manufacturing, and to provide a systems engineering approach that enables continuous improvement (CI) and adaptability to change. The systems engineering methodology developed in this paper seeks to replace the use of the word “lean” to describe the result of manufacturing system design. Current research indicates that within three years of launch, ninety percent of “lean implementations” fail. This paper provides a methodology that leaders, managers, and engineers may use to sustain their manufacturing system design and implementation.