Reliability HotWire

Issue 105, November 2009

Tool Tips

* Is there a quick way to edit the properties defined in Blocks, Policy Resources and Templates in a BlockSim project?

In BlockSim, the Item Properties Table allows you to view and/or edit the properties of the blocks in the Diagram Sheet(s), Fault Tree Sheet(s), Template(s), Maintenance Template Sheet(s) and Policies within the current project. This provides you with another way of viewing and editing properties without having to open a separate window for each item. Any changes made to properties via the Item Properties Table will be applied to the corresponding properties window and any changes made via a properties window will be reflected in the Item Properties Table.

To open the Item Properties table, choose Project > Item Properties Table.

BlockSim Item Properties Table window

You can specify which columns will appear in the Item Properties Table worksheet from the Select Visible Columns window (Edit > Select Visible Columns). For example, the Select Visible Columns window for Templates looks like this:

BlockSim Select Visible Columns window

* What is the difference between cumulative and non-cumulative data input in RGA 7?

In RGA 7, when entering data in a Data Sheet and using the default application settings, the data set is assumed to be composed of cumulative data, which means that each row shows the total amount of test time up to that point. For example, if the failure times are entered as 10, 20, 30, 40 and 50, this indicates that the first failure occurred at 10 hours of test time, the second failure occurred 10 hours later at 20 hours of test time, the third failure occurred 10 hours later at 30 hours of test time, and so on. However, you also can enter non-cumulative data, which means that each row shows the incremental test time since the last observation. In this case, if the failure times are entered as 10, 20, 30, 40 and 50, this indicates that the first failure occurred at 10 hours of test time, the second failure occurred 20 hours later at 30 hours of test time, the third failure occurred 30 hours later at 60 hours of test time, and so on. In other words, for cumulative data, you enter the time of each failure while for non-cumulative data; you enter the times between failures.

Of course, this affects how the total test time is calculated. For example, if you have a data set that contains the failure times of 10, 20, 30 and 50, if you are using cumulative data entry, the total test time would be 50 because the test time accumulates with each failure time and 50 is the last data entry point. Compare that to using non-cumulative data entry. In this case, the total test time would be 110 (the sum of the times), because the test time starts over at 0 for each failure time.

By default, RGA 7 uses cumulative data entry, but you can change that on the Calculations page of the User Setup (File > User Setup).

RGA User Setup window

Note that you can easily override the default setting for any Data Sheet in either of two ways using the Data Sheet’s control panel:

  • In the Settings Area of the Main page, you can click the Cumulative/Non-Cum option to switch between the settings.
  • On the Analysis page, you can select or clear the Input is Cumulative check box.

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