System engineering – focuses on a variety of elements, analyzing, designing, and organizing those elements into a system that can be a product, a service, or a technology for the transformation of information or control.
System – is a set of facts, principles, rules, classified and arranged in an orderly form so as to show a logical plan linking the various parts.
Computer-based system – is a set or arrangement of elements that are organized to accomplish some predefined goal by processing information.
System Elements
1. Software
– are computer programs, data structures, and related work products that serve to effect the logical method, procedure, or control that is required.
2. Hardware
– are electronic devices that provide computing capability, the interconnectivity devices (e.g., network switches, telecommunications devices) that enable the flow of data, and electromechanical devices (e.g., sensors, motors, pumps0 that provide external world function.
3. People
– are users and operators of hardware and software.
4. Database
– is a large, organized collection of information that is accessed via software and persists over time.
5. Documentation
– is a descriptive information (e.g., models, specifications, hardcopy manuals, on-line help files, Web sites) that portrays the use and/or operation of the system.
6. Procedures
– are the steps that define the specific use of each system element or the procedural context in which the system resides.
System Modeling
1. Defines the processes that serve the needs of the view under consideration.
2. Represent the behavior of the processes and the assumptions on which the behavior is based.
3. Explicitly define both exogenous and endogenous input to the model.
4. Represent all linkages (including output) that will enable the engineer to better understand the view.
· Exogenous inputs link one constituent of a given view with other constituents as the same level or other levels; endogenous input links individual components of a constituent at a particular view.
· World View WV = {D1, D2, …, Dn} D – domain
Di = {E1, E2, …, Em} E – element
Ej = {C1, C2, …, Ck} C – component
Restraining Factors in Constructing a System Model
1. Assumptions
– that reduce the number of possible permutations and variations, thus enabling a model to reflect the problem in a reasonable manner.
2. Simplifications
– that enable the model to be created in a timely manner.
3. Limitations
– that help to bound the system.
4. Constraints
– that will guide the manner in which the model is created and the approach taken when the model is implemented.
5. Preferences
– that indicate the preferred architecture for all data, functions, and technology.
