Chapter 7: The 30 elements of systems engineering ISE 443 / ETM 543 Fall 2013

7.1 Overview Architecture and construction of systems. Systems approach … 7 key features See pg. 193 3 key aspects 443/543– 6

7.2 SE perspectives 2 representations of SE perspectives Mil-Std-499B Revisited Broader view of interrelated systems 4 main features to systems engineering Variety of inputs and outputs exist NASA mission design process Built in 3 phases: Conceptual design Mission analysis Definition process Focuses attention on mission analysis (often overlooked) Focuses on front end of system life cycle 443/543– 6

7.3 30 elements Inclusive activities that are necessary over the system life cycle See Exhibit 7.1, pg. 199 See also figs. 7.2 & 7.3, pp. 200-201 It is important that the CSE master each element and also understand the interrelationship between elements.

7.3.1 Needs, Goals, & Objectives The same as the first element of the project plan. Given by the system user and must be current and appropriately stated.

7.3.2 Mission engineering Detailed articulation and analysis of the intended mission of the system that is being engineered. Main purposes are to verify that the system has legitimate missions to be executed that are not being carried out by other systems and to provide a technical basis for the full definition of requirements for the system.

7.3.3 Requirements analysis & allocation Set of activities that review existing requirements, derive new requirements, and then allocate requirements to functional elements of the system. Can determine ultimate success or failure of the system.

7.3.4 Functional analysis and decomposition Separate the “what is to be done” from the “how it is to be done” Includes defining top level functions, decomposing low level functions and subfunctions, allocating data flow appropriately. Cause the CSE to consider alternative ways to implement a given function.

7.3.5 Architecture design and synthesis Formulating alternative system architectures and then evaluating them for system requirements satisfaction. Can involve various technologies and concurrent engineering considerations. Concurrent engineering is considered as one of the 30 key elements of SE. Does not include selection of a preferred architecture.

7.3.6 Alternatives analysis and evaluation Decides the preferred system architecture. It can use TPM, LCC, risk analysis, ILS, and RMA, etc. Not enough to simply select the architecture, but also must explain why the architecture was selected.

7.3.7 Technical Performance Measurement Underlying basis for evaluating the performance of the architecture alternatives. Key ingredient in selecting more detailed design parameters. TPP – additional measures represented by the parameters upon which the TPM are dependent. Load is a special consideration Often involves computer simulation and models.

7.3.8 Life cycle costing 3 main categories of cost RDT&E Acquisition or procurement O&M Evaluate a system using a LCC model Looks at the cost elements of the system Years of useful life of the overall system and subsystems Utilize various CERs to develop the necessary cost estimates Example – COCOMO

7.3.9 Risk analysis Main categories Schedule Cost Performance Societal Most difficult is performance because it leads to both scheduling and cost risks Each risk is evaluated and given a probability level of occurrence and consequence Societal risk is risk to public that can result from deployment of the system.

7.3.10 Concurrent engineering Concurrent Engineering is ‘a systematic approach to the integrated, concurrent design of products and their related processes, including manufacturing and support’, and essentially attempts to involve all parties with a role to play throughout the system life cycle. (Justin Blount) 443/543– 6

7.3.11 Specification development Specification Development is used to continue the design after system architecture selection. It usually involves three categories: hardware, software, and human. (Justin Blount) 443/543– 6

7.3.12 Hardware, software, and human engineering This element refers to the design and construction of subsystems as well as the components that make up these subsystems. (Ryan Stapleton) (there’s more to it than this … the challenge to the class is to find at least 1 more thing to say …) 443/543– 6