System effectiveness is a measure of the ability of a system to achieve a set of specific mission requirements.

• System effectiveness is a function of:

1. Availability
2. Dependability

• Reliability & Maintainability (R&M) considerations

1. Both R&M need to be continually reviewed to ensure high availability
2. R&M must be evaluated over the system life cycle, rather than merely from the standpoint of initial acquisition

• Factors influencing system effectiveness
• System performance (design adequacy)

1. Technical Capabilities
a) Accuracy
b) Range
c) Invulnerability to countermeasures
d) Operational simplicity

2. Possible Limitations on Performance
a) Space and weight requirements
b) Input power requirements
c) Input Information requirements
d) Requirements for special protection against shock, vibration, low pressure, and other environmental influences

• Operational readiness

1. Reliability
a) Failure-free operation
b) Redundancy or provision for alternative modes of operation

2. Maintainability
a) Time to restore failed system to satisfactory operating status
b) Technical manpower requirements for maintenance
c) Effects of use cycle on maintenance. (Can some maintenance be performed when operational use of the system is not required?)

3. Logistic Supportability

• System Cost

1. Development cost, and particularly development time, from inception to operational capability
2. Production cost
3. Operating and operational support costs

• Optimization of system effectiveness

The optimization of system effectiveness is important throughout the system life cycle, from concept through the operation. Optimization is the balancing of available resources (time, money, personnel, etc.) against resulting effectiveness parameters (performance, operational readiness, etc.), until a combination is found that provides the most effectiveness for the desired expenditure of resources. Thus, the optimum system might be one that:

1. Meets or exceeds a particular level of effectiveness for minimum cost, and/or
2. Provides a maximum effectiveness for a given total cost optimization

The optimization process as a feedback loop consisting of the following three steps:

1. Designing many systems that satisfy the operational requirements and constraints
2. Computing resultant values for effectiveness and resources used
3. Evaluating these results and making generalizations concerning appropriate combination of design and support factors, which are then fed back into the model through the feedback loops

Optimization also can be illustrated by the purchase of a new car or, more specifically, by putting into precise, quantifiable terms the rule, or criteria, that will be followed in the automobile selection process. Although automobiles do have quantifiable characteristics, such as horsepower, cost, and seating capacity, they are basically similar in most cars of a particular class (lowprice sedans, sports models, etc.).

Thus, the selection criteria essentially reduce to esthetic appeal, prior experience with particular models, and similar intangibles. In the same sense, the choice of best design for the weapon system is greatly influenced by experience with good engineering practices, knowledge assimilated from similar systems, and economics. Despite this fuzziness, the selection criteria must be adjusted so that:

1. The problem size can be reduced to ease the choice of approaches
2. All possible alternatives can be examined more readily and objectively for adaptation to mathematical representation and analysis
3. Ideas and experiences from other disciplines can be more easily incorporated into the solution
4. The final choice of design approaches can be based on more precise, quantifiable terms, permitting more effective review and revision, and better inputs for future optimization problems

The choice of parameters in the optimization model also is influenced by system definition. The automobile purchaser, for example, may not consider the manufacturer’s and dealer’s service policies. If these policies are considered, the system becomes the automobile plus the service policies. If service policies are not considered, the system consists only of the automobile.

The optimization of system effectiveness is a highly complex problem; there is a degree of interaction among the factors which enter into consideration of this problem. The actual techniques used to optimize system effectiveness will be described in greater detail elsewhere in this blog. Examples include basic mathematical and statistical concepts, simulation, queuing theory, sequencing and Markov processes. These techniques are not peculiar to system effectiveness optimization, nor are they limited to system engineering.

The remaining sections of this blog will expand upon these top level system effectiveness concepts, in particular:

1. basic reliability/maintainability/availability theory
2. practical application of the theory in terms of the design methodology and procedures of reliability engineering at the equipment and system level
3. procedures for insuring that inherent reliability is not degraded during production and field deployment of systems
4. steps that management must take to insure the acquisition and deployment of reliable systems at minimum life cycle cost

References:

1. MIL-HDBK-338, Electronic Reliability Design Handbook, 15 Oct 84
2. Bazovsky, Igor, Reliability Theory and Practice
3. O’Connor, Patrick, D. T., Practical Reliability Engineering
4. Birolini, Alessandro, Reliability Engineering: Theory and Practice