OR logic gate

The immediate causes of the TOP event are shown in the fault tree with thek relationship to the TOP event. If any one of the immediate causes results dkecdy in the TOP event, the causes are connected to the TOP event with an OR logic gate. If all the immediate causes are requked for TOP event occurrence, then the causes are connected to the TOP event with an AND logic gate. Each of the immediate causes is then treated in the same manner as the TOP event, and its immediate, necessary, and sufficient causes are determined and shown on the fault tree with the appropriate logic gate. This development continues until all intermediate fault events have been developed into thek basic causes. 

Jlidat N, Hliwa M, Joachim C (2009) A molecule OR logic gate with no molecular rectifier. Chem Phys Lett 470 275... 

This remarkable molecular memory was preceded by two other related examples of addressable molecular electronics from the Stoddart and Heath groups in collaboration with Hewlett-Packard scientists. First in 1999 a [2] rotaxane based system was configured into molecular AND and OR logic gates,63 then in 2000 a [2] catenane based molecular switch was reported.64 The molecular basis for the operation of this switch is the same as in 11.67, namely reorientation in response to reduction of... 

Fig. 15 An Enabled OR logic gate and corresponding truth table.

Figure 28. Plan of an OR logic gate with a cryptand receptor.

On the other hand, the Specific and Management branches are regarded as the two main branches in MORT (see Figure 2). Specific control factors are broken down in to two main classes a those related to the incident or accident (SAl), and b those related to restoring control following an accident (SA2). Both of them are under an OR logic gate because either can be a cause of losses. 

The OR logic gate defines the situation whereby the output event or contributory factor will exist if any one of the input contributory factors is present. 

OR logic gate A device that produces an output of 1 when at least one of the inputs is 1. 

Fig. 12 (A) The polarization curves of the biofuel cell with the pH-switchable cathode obtained at different pH values generated in situ by the immune-OR-logic gate (a) pH 4.5, (b) pH 5.8. (B) Electrical power density generated by the biofuel cell on different load resistances at different pH values generated in situ by the immune-OR-logic gate (a) pH 4.5, (b) pH 5.8. Inset The maximum electrical power density produced by the biofuel cell upon different combinations of the immune input signals. (Adapted from ref. 77 with permission Copyright American Chemical Society, 2009).

In the second category, specific system safety performance requirements were elicited through the review of mitigations/protection measures in the hazard log. Those mitigations/protection measures that are related to novel equipment, or new processes, or any novel environment states within which the conventional equipment or a process is to operate, were converted into safety requirements. Those safety requirements that are related to novel equipment were further analysed in order to facilitate the representation of these in the QRA, either as base events or logical gates. 

Though the equivalent EN structures look the same for the two logic gates in Figure 1, the Conditional Belief Mass Tables (CBMTs) are different. The CBMTs for AND and OR logic gates are defined and shown respectively in Tables 1 and 2 in which AT means normal, F means failure and A, F means that the system is exclusively in one of the two conditions without distinguishing exactly which. This allows us to express uncertainties on the states of events in FTs. 

---