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Smith, David J.
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Reliability, Maintainability and Risk: Practical Safety-Related Systems Engineering Methods

David J. Smith
  • Book
  • B-ELS-043
Published 2011-08-01 by Elsevier in United Kingdom
This book provides engineers with the safety and risk assessment tools and techniques they need to work effectively in any safety or reliability critical environment. These tools are primarily statistical. Where David Smith’s book succeeds is by meeting the needs of an applied audience by setting these tools in the context of the design and operation of safety related processes and systems. Now in its Eighth Edition, this is regarded as the core reference in this field, and the success of its approach is reflected in the popularity of this standard work. It deals with all aspects of reliability, safety-related systems, and the assessment and management of risk in a simple and straightforward way, pre-supposing no prior knowledge and dealing simply and realistically with numerical data by using the minimum of mathematical and technical jargon.
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A Microprocessor Based Soil Moisture Sensor System for Space Based Plant Growth Units

Orbital Technologies Corp.-Robert C. Morrow, Thomas M. Crabb, Ronald J. Anderson, David J. Smith
Published 2001-07-09 by SAE International in United States
A soil moisture sensor system consisting of small heat-pulse probes, a microcontroller, and software for data acquisition and signal conditioning was developed for use in space based plant growth units. The microcontroller allows the sensors to be used in a control application with minimum time demands on the control subsystem. A single digital serial link may be shared by up to 16 microcontrollers with 8 sensors each, for a total of 128 sensors. The microcontroller independently applies heat cycles to determine the current moisture level, and responds to a request from the computer with the last known value. Using the microcontroller system, repeatability testing was completed for wet 1–2 mm arcillite. The standard deviation in wet arcillite over a 16-hour period was about 3%. Software filtering can be used to reduce the standard deviation further. In addition to determining root zone moisture levels, this system can also be used to monitor root zone temperature and to detect wavefront movement through a dry rooting medium.
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