FaultTree+ Friday

Today I would like to address one of the most commonly asked questions by new users of our FaultTree+ software, which is: Copy and Paste vs. Copy and Paste Special. When used correctly Copy and Paste and Copy and Paste Special can be a huge time saver. If used incorrectly this feature can unintentionally be introducing Common Cause Failures (CCF) which can kill the reliability of a system or create copies of existing events or gates, which were intended to be CCF, making your tree more reliable than it should be.

Copying and Pasting a gate or event will cause the same gate or event to appear in different parts of the tree. Pump1 will be our example, if we Copy and Paste Pump1 from gate GT1 and paste that pump under gate GT3. Pump1 would now be listed under 2 separate OR Gates.

As you can see in the example below the event named Pump1 has been Copied and Pasted under gate GT3. The event Pump1 has the exact same name in both events making Pump1 a CCF. Using Copy and Paste is representing the same event in two different branches of this fault tree.

FaultTree1

Copy and Paste Special on the other hand creates a copy of Pump1. This is not the same event but an identical event. As you will see below I have used Copy and Paste Special to add a copy of Pump1 under gate GT1 to gate GT2, the new identical pump is named Pump2 not to be confused with the event Pump1 under gate GT1 and GT3 . Pump2 is an identical in every way to Pump1 but is not the same pump. In this case Pump2 would not create a CCF. Please note that when using Paste Special the software has automatically renamed event Pump1 to Pump2. The new gate or event can use any naming convention you would like as long as it is not the same name as an existing event. When 2 gates or events have the exact same name the software recognizes those gates or events as the same gate or event.

Faulttree2

 

 

 

Tech Tuesday: The Grid Control

Howdy, folks. This will be the first installment of what we hope will become a regular feature around here. Each Tuesday, look for an article highlighting a technical aspect of our software. This may be a demonstration of a feature, an explanation of the mathematics that power the tools, or some comments on technical support questions that we’re frequently asked.

Today, I’ll be talking about the Grid Control feature of our Availability Workbench and Reliability Workbench tools. If you’ve used our AvSim or FaultTree+ software, you know the power of the tool, and the usefulness of the diagram view to be able to create and edit intricate Fault Tree or Reliability Block Diagrams (RBDs). However, sometimes you may find that you have to do some task, such as text entry, or finding and replacing some information, that can be cumbersome to perform in the diagram view.

For instance, suppose you’ve created a large, multi-page Fault Tree, and now you want to add unique IDs and descriptions to all the gates and events, so you can identify what each one represents. To do this in the diagram view, you’d need to locate each item individually, double-click to open the Properties dialog for the gate or event, set the ID and description, click “OK” to close the dialog, find the next item, rinse, and repeat. There’s a lot of back-and-forth between mouse and keyboard, and hunting through the diagram for the items you want.

Properties

The Event Properties dialog from FaultTree+

 

The Grid control helps with this by providing a tabular format for editing data, similar to what you’d see in Microsoft’s Excel or Access products. Each gate or event appears on one line of the grid, and you can use the cursor keys, or the tab key, to navigate the records and fields. To edit some text, simply highlight a field with the mouse or keyboard and start typing, or press Enter on your keyboard.

Grid

The Grid view in FaultTree+

From the grid view, you can use the table selector to choose which data you want to display. This might be the Gates, Events, or Failure Models table in FaultTree+ , or the RBD Blocks or Failure Models table in AvSim.

TableSelector

Grid Table selector

With a given table selected, you can refine which records should be displayed by using the “Filter Grid by Tree Control Selection” option, found in the Grid menu. This mouthful-of-a-name simply means that data will only be displayed in the Grid if it’s relevant to the selection in the tree control on the left hand side. For instance, selecting a particular gate in the Fault Tree hierarchy will only show events under that gate, or selecting a Failure Model group in the AvSim project will only display failure models in that group.

FilterByTreeControlSelection

“Filter by Tree Selection” turned on; note how only events logically dependent on the selection on the left are displayed in the grid.

There are plenty more options in the Grid view that allow you to choose what data is displayed. You can use the Grid Layout options to choose what columns should be displayed, and what their order should be; the Grid Filter provides further methods of filtering records; and the Grid Sort allows you to choose how the records are sorted. And any custom grid layout, filtering, or sorting you’ve created can be saved, so you can share it with your colleagues or transfer it to a new computer. You can even copy and paste data directly from the Grid view to a spreadsheet application like Microsoft Excel.

GridOptions

The options under the Grid menu. Layout Options, Filter, and Sort are all near the top. Options to import and export grid layouts are near the bottom.

There’s even a Find & Replace feature, for when you need it. The cool part is, when you use Find & Replace, it will only apply to the currently-displayed records. If you use a filter to hide certain rows, they won’t be included in the replacement.

FindandReplace

The Find & Replace dialog. This works exactly like you’d expect.

And for those times when you want the Properties dialog, you can just double-click the grey space to the left of a grid row to open the Properties dialog for the item.

Why don’t you take a look at the Grid control, and try it out? I’ve found it to be a great tool to use when quickly building or editing a project.

Monte Carlo Simulation

Happy MLK jr day,

For those of you working today I thought I would give a little background on Monte Carlo Simulation (MCS). I have to admit that when asked I have tied MCS back to the gambling industry more than once. It sounds like a good story, however, it turns out the name comes from the resemblance to the act of playing and recording your results in a real gambling casino.  MCS techniques are often used in physical and mathematical problems and are most useful when it is difficult or impossible to obtain a closed-form expression, or in-feasible to apply a deterministic algorithm. Monte Carlo methods are mainly used in three distinct problem classes: optimization, numerical integration and generation of draws from a probability distribution.

The modern version of the Monte Carlo method was invented in the late 1940s by Stanislaw Ulam, while he was working on nuclear weapons projects at the Los Alamos National Labs. It was named by Nicholas Metropolis, after the Monte Carlo Casino, where Ulam’s uncle often gambled.  Immediately after Ulam’s breakthrough, John Von Neumann understood its importance and programmed the ENIAC computer to carry out Monte Carlo calculations.

So although gambling is a reference it’s not the reason for or used in the gaming industry… we at Isograph use MCS techniques to solve problems that cannot be solved using quantitative methods. Optimizing Preventive Maintenance Intervals, deciding the perfect number  of spares to have and where to keep them as well as optimizing the configuration of your system are just a few of the problems we can solve with the Availability Workbench using Monte Carlo Simulation. However, we cannot tell you where to place your bets or what number to choose on the Roulette Wheel.

The following is a short demonstration as to how we use MCS together with FMEA’s for RCM analysis or Block Diagrams to model complex systems logic.

Availability Workbench using Monte Carlo Simulation

 

Isograph at RAMS 2014

For almost 2 decades Isograph has been supporting the RAMS conference in various locations around North America. The week of January 27 Isograph will again be attending RAMS 2014 which will be held at The Broadmoor Hotel in Colorado Springs, Colorado. In addition to the exhibits the conference will offer tutorials, technical presentations, CEUs and certifications such as the ASQ Certification Exams – ASQ Certified Reliability Engineer (CRE), Certified Six Sigma Black Belt (CSSBB) and Certified Six Sigma Green Belt (CSSGB).

For more information on RAMS please go to www.rams.org

Broadmoor Hotel