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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.
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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, online 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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