Monthly Archives: September 2009

I am giving a presentation tonight (Sept 30) at the IEEE Reliability Society meeting at the HP Oak Room in Cupertino, CA. Email me if you want details on the event or need directions. It is a FREE event.  I started a linked-in discussion on this same topic and I posted a blog on our site about this so sorry if you are getting this from a few different angles.

Given the short notice, I’m guessing most of you will not be able to attend but I would like to start a discussion about this topic.   Here is a link to a few Green presentations we have given, including tonight’s presentation

Part of the motivation for this talk is that today, the topic of Green is discussed more and more. Every day we hear about companies “going green”. But what does this really mean? You can hardly go to a website today without finding claims such as “we are going green”. The problem is there are no common definitions of what “Green” is and if we treat it this way, then the “Green Revolution” will come and go and there won’t have been much of an impact on our environment.

Leading clean tech specialists Woody Clark and Thomas Friedman agree that we need to start doing something immediately and the govt needs to help. Both are using global warming as one of their principle scare tactics. Is global warming real? We won’t debate that here but what is real is that energy consumption is going up exponentially along with the growth of China and India and other developing nations. Both are saying that the US must take the lead!

Friedman criticized the Bush administration for not reacting to 9/11 from an energy point of view. According to Friedman, the US had a golden opportunity to reduce our dependency on oil and we blew it.

Now we must take the lead with alternative energy solutions. China and India are looking closely at us and will likely follow. But we need to show leadership. The wrong move now could be costly later on. But what do we need to do and how do we do it?

And EPEAT is the newest buzzword that is getting a lot of attention, but is this just another fad with no teeth?

Today there are no standards set for Quality/Reliability in the Green movement. If the product fails prematurely, they have means of disposing of it but why not work on preventing it from failing in the first place ?

Woody and Thomas never mention reliability in their books. There is a big gap and everyone in this room will be playing a roll of filling that gap in the next 10-15 years.

My talk addresses this very subject – “Going Green” has many implications, from the materials being used to the type of energy being used and the quantity being consumed. And each aspect of “Going Green” has reliability implications. In fact, any time we change material properties or design concepts, there are inherent reliability risks that need to be addressed.

PS – I am giving the talk again at the annual Accelerated Stress Testing and Reliability Workshop in New Jersey next week (THIS TALK AND THE ENTIRE CONFERENCE ARE AVAILABLE VIA WEBINAR if you would like to attend so let me know if you need details on this). I would very much appreciate any feedback/advice you can give me on this so that I can incorporate your opinions into my talk. Specifically, here are a few polling questions that I would like you to answer for my research:

1) Do you believe the Green movement today has real teeth or is it still a lot of talk without much action

2) Do you believe we need reliability and quality guidelines or standards for the green movement

3) Do you believe that Obama should regulate the industry so as to “fuel” the green movement and get us away from fossil fuels. One such way is either tax breaks for green or tax hits for non-green, the most obvious being to tax gasoline.

One of our readers, John Hurtley from Tolomatic,  wrote the following:

We have been doing design reliability testing for sometime now. We’re using a software tool from ReliaSoft that works well in designing the test and analyzing the results. A major problem within our wall is selecting a reliability level to be achieved and the applied confidence bounds that should be used for our product / industry. Does anyone know of a resource that could help in providing a bench mark for reliability? Ideally a list of industries and the reliability levels typically applied. Or, a define method / tool that would assist us to determine our reliability requirements from within.

Mike Silverman’s response:

Reliability goal setting is not something you will find in any specific tool.  This is something your company must decide on based on many different factors.  There are three different ways you can develop a reliability goal:

There are two ways to approach fault analysis — Failure Modes, Effects and Criticality Analysis (FMECA), which is currently the most common approach, and Fault Tree Analysis (FTA). Both look at the effects of component failures on a system, but come at it from different ways. FMECA starts from the lowest levels of the system and considers the effect at the top level of the system of a failure at the lower level. FTA starts with a possible failure mode of the system, and then works down to see what could cause it. The Reliability Toolkit1, gives selection criteria for when to use either of these two approaches.

  • The primary concern is safety of public or operating and maintenance personnel
  • A small number of clearly differentiated “top events” can be identified
  • Completion of a functional profile is of critical importance
  • There is a high potential for failure from “human error”
  • There is a high potential for failure from “software error”
  • The primary concern is a quantified “risk evaluation”
  • Product functionality is highly complex and/or it contains highly-interconnected functional paths

On the other hand, the FMECA is the preferred approach when:

  • “Top events” cannot be explicitly defined or limited to a small number
  • The primary concern is the identification of “all possible” failure modes
  • The product has little human or software intervention

It is clear that, from this analysis, FTA is the more appropriate approach in many cases.

In addition, FTA is an easier and faster mode of analysis for (at least) two reasons. Firstly, it focuses on a select subset of the possible modes, those that have a “catastrophic” consequence. Secondly, it is my experience that it seems more relevant to the engineering mind as the consequence provides a focus. Also, it is generally done graphically so is easier to visualize than the tables of a FMECA.

Even more so than a FMECA, the FTA is an invaluable tool in the initial design stages as it can be applied even at the block diagram stage to determine critical areas. Unlike a FMECA, operator, software and external input effects can be easily included. An added benefit is that the FTA provides a basis for maintenance troubleshooting procedures.


1. Reliability Toolkit: Commercial Practices Edition, Rome Laboratory & Reliability Analysis Center.