Definition failure

In applying the definition of rehabihty, the concept of adequate performance must be estabhshed clearly. Products usually do not fail suddenly, but degrade over time. Gasket leaks on equipment, for example, may start as a slow weep and increase in volume over time. The point at which this undesirable occurrence is called a failure must be clear before rehabihty can be measured objectively. Changing the failure definition for a product changes its rehabihty level, although the product itself has not changed. 

Due to such subtleties, the need to develop well-defined basic events, failure modes, and equipment boundaries prior to data encoding cannot be overemphasized. Familiarity with failure definitions and failure severities will be extremely helpful to the analyst. Figures 2.1 and 2.2, reprinted from IEEE Std. 500-19845, list a large number of failure modes by failure severity and may help encode failures. IPRDS also contains helpful information on failure encoding. Information on some equipment boundaries may be found in the Data Tables in Section 5.5. 

Bellomo R, Ronco C, Kellum JA, et al. Acute renal failure—definition, outcome measures, animal models, fluid therapy and information technology needs the Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group. Crit Care 2004 8 R204-R212. 

Documenting the expected performance of the system, process, or equipment item the system or process restraints and the failure definitions of the equipment items, the process, or the system. 

A panel of experts has recently published a consensus opinion based on a literature review as to when to consider patients to have failed IM and to then be considered for alternate therapies. In this study, failure was defined as lack of a hematologic response after 3 months of IM, less than a complete hematologic response or no cytogenetic response (>95% positive PH chromosome) after 6 months of IM, less than an MCR after 12 months, and less than a CCR after 18 months. The development of mutations, loss of a CCR, or loss of a complete hematologic response at any time was also considered a failure. Definitions for a suboptimal response and warning situations such as additional chromosome abnormalities were also listed (Table 2) (31). 

Bernuau, J., Rueff, B., Benhamou, J.-R Fulminant and subfulminant liver failure definitions and causes. Semin. Liver Dis. 1986 6 97-106... 

Mehta RL, Chertow GM. Acute renal failure definitions and classification time for change J Am Soc Nephrol 2003 14 2178-87. 

Participate in the development of failure definition and scoring criteria document. 

Failure definition a general statement of what constitutes a failure of the item in terms of performance parameters and allowable limits for each specified output Failure effect consequence(s) a failure mode has on the operation, function, or status of an item ... 

A required function specifies an item task. A correct, exact and unequivocal definition is a primary starting point for all dependability definitions as well as for a right failure definition. Operation conditions affect significantly both dependability and especially possible failure occurrence, hence the reason why they have to be determined very thoroughly. We concentrate on the main and support functions (Valis Bartlett 2010) in terms of failure occurrence and function loss of polymer composites with natural fibres. 

A failure (definition 1.1) is an external manifestation of an observable error (the lEC 61508 [lEC 98] standard speaks of an anomaly). 

Define the system to be analyzed. A System Design Document should provide a complete system definition, which includes identification of internal and interface functions, expected performance at all system and subsystem indenture levels, system restraints, failure definitions, operational tasks, environmental profiles, equipment utilization, and the functions and outputs of each item. 

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