Triple redundancy

To help avoid the possibility of human error, automation in plant-safety S5 tems is now an area of practicing triple redundancy. Triple redundancy was formerly observed only with control of high-performance mUitaiy aircraft sterns. Now, increasingly, it pa off with land-based control i stems that are safety, operational, or control in scope. See THple Redundancy. 

Special high rehabiUty systems have been developed for safety shutdowns, eg, triple modular redundant systems (TMRS), which are designed to be... 

Fig. 5. Stmcture of a triple modular redundant system (TMRS). See text.

Triple Modular Redundant (TMR) - A system that employs a 2 out of 3 (2003), voting scheme to determine the appropriate output action. It is based on the application of three separate operating systems running in parallel. 

One can argue, however, that the improved description of the triple-correlation term in the Reynolds-stress model and the improved scalar-flux model justify this redundancy. 

Since caroviologens are rather fragile compounds, they can be protected from the environment by inclusion into polyanionic derivatives of (J-cyclodextrin in a rotaxane fashion 102 [8.156]. Also, in the design of molecular devices, it may be desirable to introduce some extent of redundancy in order to reduce the risk of device failure. This is the case in the tris-carotenoid macrobicycle 103 that represents a sort of triple-threated molecular cable whose crystal structure 104 has been determined. It forms a dinuclear Cu(i) complex 105 in which the bound ions introduce a positive charge at each of the species, a feature of potential interest for transmembrane inclusion [8.157]. 

The process can be continued. If the unit cell is tripled, the band will fold as in 76a. If it is quadrupled, we get 76b, and so on. However, the point of all this is not just redundancy, seeing the same thing in different ways. There are two important consequences or utilizations of this folding. First, if a unit cell contains more than one electronic unit (and this happens often), then a realization of that fact, and the attendant multiplication of bands (remember 74 - 73 -> 76a - 76b), allows a chemist to simplify the analysis in his or her mind. The multiplicity of bands is a consequence of an... 

The RI constant, which relates the RI units to sample concentration, was determined by the dnjdc method of Wyatt Technology. The RI constant exhibited some variation at times, so that its value hacT to be adjusted in order to match the calculated mass with the injected mass. This variation was attributed to an intermittently faulty RI detector. The triple detection system had sufficient redundancy that accurate values of and [r ] could be obtained even when one component was not working well. 

SOFTWARE SYSTEMS SAFETY - TRIPLE REDUNDANCY FOR SOFTWARE ... 

A document called "The Engineers Responsibility for Computer Based Decisions" (17a), published by the Institution of Chemical Engineers, recommends triple redundancy - with voting - for software in "critical" applications. 

None of the documents noted above covers the questions specific to V V for knowledge-based expert systems, although many of the concepts discussed are applicable. And triple redundancy is useless unless the top level problems of safety have been addressed in system specification s. 

Such results show that software-based techniques combined with HETA can be used in harsh environments and allow designers to reach fast fault diagnosis and correction. When comparing to hardware-based techniques, such as Xilinx Triple Modular Redundancy (XTMR) with scmbbing, that require modifications to the microprocessor s hardware, we can notice an area reduction higher than 66% and still acceptable fault coverage of 96.9%. On the other hand, the hardened application takes 1.48 times the original time to execute and 6.5 % more area to implement the OCFCM hardware module. 

KASTENSMIDT, E STERPONE, L. CARRO, L. SONZA REORDA, M. On the optimal design of triple modular redundancy logic for SRAM-based FPGAs. In DESIGN, AUTOMATION AND TEST IN EUROPE CONFERENCE, 2005, DATE 2005. Proceedings... New York, USA ACM Press, 2005, pp. 1290-1295. 

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