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| In this
issue: |
Issue
11, January 2002 |
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Reliability HotWire is a service of ReliaSoft
Corporation
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| Hot Topics |
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Customer
Usage Profiling
An important requirement for designing useful reliability tests is to have a good idea
of how the product is actually going to be used in the field. The tests
should be based on a realistic expectation of the customer usage, rather
than estimates or "gut feelings" about the way the customer will
use the product. Tests based on mere speculation may result in a product
that has not been rigorously tested and consequently may run into
operational difficulties due to use stress levels being higher than
anticipated. On the other hand, tests that are designed with a strong
basis of information on how the product will be used will be more
realistic and result in an optimized design that will exhibit fewer
failures in the field. In this article, we take a look at using customer
usage information for reliability
applications.
To
read more, see http://www.weibull.com/hotwire/issue11/hottopics11.htm
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| Reliability
Basics |
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| The
purpose of this section is to offer background and advice to the novice
reliability engineer.
Nonparametric Analysis
In the last several issues of Reliability HotWire, we have
looked at various ways of performing parameter
estimations on life data sets. Nonparametric analysis allows the analyst
to characterize life data without assuming an underlying distribution.
This can be advantageous because it avoids some of the dangers inherent in an
analysis where an inappropriate distribution is assumed. However, the
analysis is limited to reliability estimates only for the failure times in
the data set, thus making it impossible to make reliability predictions
outside the range of data values. While this somewhat limits the
usefulness of this method, nonparametric analysis can be used as a
benchmark against which other parametric analyses can be compared for accuracy.
To read more, see http://www.weibull.com/hotwire/issue11/relbasics11.htm
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| Tool
Tips |
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The
Tool Tips section addresses helpful hints and frequently asked questions
about ReliaSoft software products.
-
What is the
difference between "upper" and "lower" confidence
bounds, and "top" and "bottom" confidence bounds?
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In Weibull++, what does "PNZ" stand for and how does it work?
To read more, see http://www.weibull.com/hotwire/issue11/tooltips11.htm
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| Hot
News |
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Reliability
Training at GM Knowledge Center -
We are pleased to announce that once again ReliaSoft will be providing training classes for GM
employees at the General Motors Knowledge Center in Warren, Michigan. The courses offered will cover three diverse disciplines of
reliability engineering and include life data analysis, accelerated life
test data analysis and system reliability, maintainability and
availability analysis. For more information contact ReliaSoft at
+1.520.886.0410 or visit GM’s corporate intranet. Class size is limited.
The 2002 class schedule is as follows:
- February 4-7, 2002 -- Life Data Analysis & Accelerated Life Testing Analysis
- May 6-9, 2002 -- Life Data Analysis & System Reliability
- August 5-8, 2002 -- Life Data Analysis & Accelerated Life Testing Analysis
- October 14-17, 2002 -- Life Data Analysis & System Reliability
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Next
Seminar in Tucson, February 18 - 22 - The next ReliaSoft
"Master the Subject, Master the Tools" seminar will be
held in Tucson from February 18-22, 2002 at the Sheraton Hotel
and Suites. Topics for this five-day seminar include life data
analysis, accelerated life testing and system reliability,
maintainability and availability. For more information on
course content and how to register, see http://www.ReliaSoft.com/seminars/master.htm.
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ReliaSoft
at RAMS -
ReliaSoft will be participating in the 48th Annual Reliability and
Maintainability Symposium (RAMS), to be held January 28-31, 2002 at
the Seattle Westin Hotel in Seattle, Washington. ReliaSoft personnel
will be presenting papers on FRACAS systems, on-line quality tracking
and accelerated testing. Also, ReliaSoft will have a booth in the
vendors area where you can get information and demonstrations of
ReliaSoft's products and services. We hope to see you there! |
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| From
The Edge |
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In addition to the
monthly Reliability HotWire, ReliaSoft publishes Reliability Edge, a printed journal
that includes articles and information related to the field of
reliability engineering. Articles of interest in the current edition:
- Data, Where Art Thou? - As reliability
analysis tools become more capable, the availability of accurate and
timely data for analysis becomes the limiting factor in the ability to
perform effective reliability analyses. The information required for
reliability analysis is often stored in various locations within the
organization, in multiple formats that may be difficult for the
analyst to integrate. This article discusses ways and means of data
management to support timely and accurate reliability analyses. See
http://www.ReliaSoft.com/newsletter/4q2001/fracas.htm.
- Limitations
of the Exponential Distribution for Reliability Analysis -
The exponential distribution models the
behavior of units that fail at a constant rate, regardless of the
accumulated age. Although the distribution is frequently
used due to its relative theoretical and mathematical simplicity, the
exponential distribution can lead to wildly inaccurate analyses if
improperly applied. In order to avoid such inaccuracies, we need to
understand the basic constant failure rate assumption of the
exponential distribution and examine whether it is supported in our real world applications.
This article presents a discussion of these issues. See http://www.ReliaSoft.com/newsletter/4q2001/exponential.htm.
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Contribute
to Hotwire
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Contributions
Welcomed
As always, your
feedback and contributions are appreciated. ReliaSoft is able to provide the most
user-friendly reliability software packages and support because we
listen to our customers. This applies to our newsletters and
publications as well. We welcome any suggestions or contributions you may
have for Reliability HotWire.
If you have a topic or
article that you think would be useful to the readers of Reliability
HotWire, feel free to contact us. We can be reached by
e-mail at HotWire@ReliaSoft.com,
or by standard mail at 1450 S. Eastside Loop, Tucson, AZ 85710-6703, USA.
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Copyright © 2002 ReliaSoft
Corporation, ALL RIGHTS RESERVED
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