RME 7:
1- Textbook Chapter 14 Question 8:
Describe the interrelationships between the human factor requirements, the reliability requirements and maintainability requirements; that is their impact on each other. Provide some examples.
The basic design objectives for the system and its element should be compatible with the system operational requirements, maintenance and support concept and the prioritized technical performance measures; comply with the allocated design to criteria and meet all of the requirements in the various applicable specifications.
These three requirements, human factor, reliability and maintainability are design-dependent parameters, and also are considerations in system design. This system design endeavour needs an appropriate and on time application of engineering and management efforts to maximize the likelihood that the resulting system design will be operationally feasible. Operational feasibility points out that the system will perform in an effective and efficient manner in response to a given customer need. These requirements have a considerable effect on the ultimate worth of a system. The reliability is the most prominent design-dependent parameter. Whilst reliability deals with time to failure, maintainability has to do with time repair. Also usability is a parameter linking human factors with the system. In this regard, downtime and the waste of resources for maintenance stem for lack of the proper consideration of reliability and maintainability in design. Thus, maintainability and reliability are the counterpart each other. Both of these design-dependent parameters have to do with continuation of the operation and service expected from a system. In terms of human factors, reliability, maintainability and related design considerations have been applied to equipment, software and associated elements of the system. However, for the system to be effective and robust during service, the human element needs to be addressed from a usability and operability perspective. This involves an understanding of the interfaces between the human and other elements of the physical system. Consequently, they are necessary in designing for operational feasibility during the system life cycle.
For example: when considering the operating of a motor vehicle, a set of related tasks might involve * Applying the appropriate pressure on the accelerator in order to maintain the desired vehicle speed * Shifting gears when necessary in order to maintain engine rpm * Turning the steering wheel as required enabling the motor vehicle to move in the desired direction
2- In order to fully specify a system it is essential to specify its availability, its reliability and its maintainability. Comment on this statement.
A primary objective in design for operational feasibility is to ensure that the system is available and operating in an effective and efficient manner as required in achieving its specified mission objectives. The realization of an availability requirement depends on two factors: 1. The inherent reliability of the applicable system and 2. Maintainability or the ability of that system to be maintained and/or repaired in the event of failure and returned to service rapidly and efficiently.