Brittle system

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Brittle systems theory creates an analogy between communication theory and mechanical systems. A brittle system is a system characterized by a sudden and steep decline in performance as the system state changes. This can be due to input parameters that exceed a specified input, or environmental conditions that exceed specified operating boundaries. This is the opposite of a gracefully degrading system. Brittle system analysis develops an analogy with materials science in order to analyze system brittleness.[1] A system that is brittle (but initially robust enough to gain at least some foothold in the marketplace) will tend to operate with acceptable performance until it reaches a limit and then degrade suddenly and catastrophically. The table below illustrates the concept behind the analysis using an example of a communication system.

Materials Science Target System Brittle Systems Analysis Materials Science Quantification
Stress Interbyte jitter, EMI, number of slaves, etc. Amount parameter exceeds tolerance Force per unit area within a body
Toughness Ability to withstand the above System robustness Ability to absorb energy up to failure
Hardness* Constant latency, throughput with stress in tolerance Level of performance within tolerance Resistance to deformation
Ductility* Gradual reduction in latency, throughput as stress exceeds tolerance Level of performance out of tolerance Fracture strain or reduction of area at fracture
Plastic strain Latency, throughput are permanently degraded System cannot recover from degradation Deformation between particles in a body relative to length
Reversible strain Latency, throughput are temporarily degraded System can recover from degradation Same as above, but returns to normal after force removed
Brittle fracture Sudden steep decline in latency, throughput Sudden steep decline in performance There is no reduction of area when material breaks
Ductile fracture Graceful degradation in latency, throughput Graceful degradation in performance The area at the point of fracture gradually reduces to zero
Brittleness* Hardness over ductility Ratio of hardness over ductility Ratio of hardness over ductility
Deformation Degradation in latency, throughput Degradation in performance Change in shape of a material
Young's modulus Stress (jitter/EMI) over reduction in latency and throughput Amount of tolerance exceeded over degradation Measure of the stiffness of an elastic material

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  1. ^ Stephen F. Bush, John Hershey and Kirby Vosburgh, Brittle System Analysis, arXiv:cs/9904016

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