Gaithersburg, MD, United States
Gaithersburg, MD, United States

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Xapsos M.A.,NASA | Stauffer C.A.,MEI Technologies Inc. | Jordan T.M.,EMP Consultants | Adams Jr. J.H.,NASA | Dietrich W.F.,U.S. Navy
Proceedings of the European Conference on Radiation and its Effects on Components and Systems, RADECS | Year: 2011

A model is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models. © 2011 IEEE.


Xapsos M.A.,NASA | Stauffer C.A.,MEI Technologies Inc. | Jordan T.M.,EMP Consultants | Adams Jr. J.H.,NASA | Dietrich W.F.,U.S. Navy
IEEE Transactions on Nuclear Science | Year: 2012

Analysis is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models. © 2012 IEEE.


Pellish J.A.,NASA | Xapsos M.A.,NASA | Stauffer C.A.,MEI Technologies Inc. | Jordan T.M.,EMP Consultants | And 7 more authors.
IEEE Transactions on Nuclear Science | Year: 2010

We use ray tracing software to model various levels of spacecraft shielding complexity and energy deposition pulse height analysis to study how it affects the direct ionization soft error rate of microelectronic components in space. The analysis incorporates the galactic cosmic ray background, trapped proton, and solar heavy ion environments as well as the October 1989 and July 2000 solar particle events. © 2010 IEEE.


Reed R.A.,Vanderbilt University | Weller R.A.,Vanderbilt University | Akkerman A.,Soreq NRC | Barak J.,Soreq NRC | And 25 more authors.
IEEE Transactions on Nuclear Science | Year: 2013

This anthology contains contributions from eleven different groups, each developing and/or applying Monte Carlo-based radiation transport tools to simulate a variety of effects that result from energy transferred to a semiconductor material by a single particle event. The topics span from basic mechanisms for single-particle induced failures to applied tasks like developing websites to predict on-orbit single event failure rates using Monte Carlo radiation transport tools. © 1963-2012 IEEE.


Xapsos M.A.,NASA | Stauffer C.,ASandD Inc. | Jordan T.,EMP Consultants | Poivey C.,European Space Agency | And 5 more authors.
IEEE Transactions on Nuclear Science | Year: 2014

The Hubble Space Telescope has been at the forefront of discoveries in the field of astronomy for more than 20 years. It was the first telescope designed to be serviced in space and the last such servicing mission occurred in May 2009. The question of how much longer this valuable resource can continue to return science data remains. In this paper a detailed analysis of the total dose exposure of electronic parts at the box level is performed using solid angle sectoring/3-dimensional ray trace and Monte Carlo radiation transport simulations. Results are related to parts that have been proposed as possible total dose concerns. The spacecraft subsystem that appears to be at the greatest risk for total dose failure is identified. This is discussed with perspective on the overall lifetime of the spacecraft. © 1963-2012 IEEE.


Barry J.,Arcadis | Mora R.G.,Imperial Oil | Carlin B.,EMP Consultants
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2014

1 This paper provides an approach for assessing and classifying riverine pipeline crossings to prioritize effective mitigation and monitoring. These processes require understanding of and accounting for channel processes, river dynamics, geomorphic principals and soil mechanics to estimate bed scour and bank erosion degradation mechanisms at water crossings and their potential effects on the pipeline. The intent of this paper is to share generic experiences in ranking water crossings based on their susceptibility to and identification of integrity threats under multiple existing and future hydrologic scenarios causing potential for pipeline exposure, spanning or damage. The intent is not to present or provide an analysis or review of the various methods for estimating channel bed or bank erosion. The details of such calculations are highly site specific and a variety of both qualitative and quantitative methods can be applied depending upon available site data, and as such, are outside the scope of the work presented here. Pipelines are static features within a dynamic environment with rivers and floodplains representing some of the most active areas within a landscape. Rivers can change course, migrate, deepen, and widen slowly over time or suddenly during large flood events. These hydrologic effects can impact existing pipelines thereby putting pipelines at risk for damage or failure. Understanding how rivers alter the landscape and transport water and sediment from the mountains to the sea provides a framework for realizing the potential toll that riverine changes can have on pipeline infrastructure. Further, integrating analysis of how rivers at specific pipeline crossing locations are likely to change can increase the effectiveness in protecting the environment during the design, construction, operation and integrity management of pipelines at river crossings. The paper provides an approach comprised of five (5) stages: 1. WC Inventory and Desktop Data Gathering 2. Screening Process: Preliminary WC Classification 3. Detailed Assessment 4. Final WC Classification, Prioritization, and Risk Assessment 5. Development of Mitigation and Monitoring Strategies This paper also presents two (2) case studies illustrating how assessing the geomorphic condition and processes of the river system being crossed by pipelines provides for a better understanding of susceptibility to existing hydro-geotechnical threats to the pipeline as well as the susceptibility for floodrelated forces in the future. The first case study illustrates how changes to a river's cross section as a result of construction activities upstream of a pipeline water crossing can cause significant and potentially damaging impacts, downstream. The second case study reinforces the importance of understanding the history of watershed and channel changes over time, both at the specific water crossing location, but also both upstream and downstream from the crossing itself to be able to identify and understand all potential threats to pipelines located within rivers and floodplains. A method for assessing and classifying the magnitude and probability of flood related risk at each case study is discussed. These cases are presented as generic examples for educational purposes only as every pipeline has its own specific characteristics conditions with jurisdiction-specific regulatory requirements requiring process customization and enhancements. Copyright © 2014 by ASME.

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