FPGAs have been shown to operate reliably within harsh radiation environments by employing single-event upset (SEU) mitigation techniques, such as configuration scrubbing, triple-modular redundancy, error correction coding, and radiation aware implementation techniques. The effectiveness of these techniques, however, is limited when using complex system-level designs that employ complex I/O interfaces with single-point failures. In previous work, a complex SoC system running Linux applied several of these techniques only to obtain an improvement of 14
Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher.
Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?
Some links on this page may take you to non-federal websites. Their policies may differ from this site.
-
in mean time to failure (MTTF). A detailed post-radiation fault analysis found that the limitations in reliability were due to the DDR interface, the global clock network, and interconnect. This article applied a number of design-specific SEU mitigation techniques to address the limitations in reliability of this design. These changes include triplicating the global clock, optimizing the placement of the reduction output voters and input flip-flops, and employing a mapping technique called “striping.” The application of these techniques improved MTTF of the mitigated design by a factor of 1.54\(\times\) and thus provides a 22.8X\(\times\) MTTF improvement over the unmitigated design. A post-radiation fault analysis using BFAT was also performed to find the remaining design vulnerabilities.\(\times\) Free, publicly-accessible full text available September 30, 2025 -
Free, publicly-accessible full text available December 1, 2025
-
FPGAs are increasingly being used in space and other harsh radiation environments. However, SRAM-based FPGAs are susceptible to radiation in these environments and experience upsets within the configuration memory (CRAM), causing design failure. The effects of CRAM upsets can be mitigated using triple-modular redundancy and configuration scrubbing. This work investigates the reliability of a soft RISC-V SoC system executing the Linux operating system mitigated by TMR and configuration scrubbing. In particular, this paper analyzes the failures of this triplicated system observed at a high-energy neutron radiation experiment. Using a bitstream fault analysis tool, the failures of this system caused by CRAM upsets are traced back to the affected FPGA resource and design logic. This fault analysis identifies the interconnect and I/O as the most vulnerable FPGA resources and the DDR controller logic as the design logic most likely to cause a failure. By identifying the FPGA resources and design logic causing failures in this TMR system, additional design enhancements are proposed to create a more reliable design for harsh radiation environments.more » « less
-
Abstract Seasonal sea ice retreat is known to stimulate Southern Ocean phytoplankton blooms, but depth‐resolved observations of their evolution are scarce. Autonomous float measurements collected from 2015–2019 in the eastern Weddell Sea show that spring bloom initiation is closely linked to sea ice retreat timing. The appearance and persistence of a rare open‐ocean polynya over the Maud Rise seamount in 2017 led to an early bloom and high annual net community production. Widespread early ice retreat north of Maud Rise in 2017, however, had a similar effect, suggesting that the polynya most impacted the timing of bloom initiation. Still, higher productivity rates at Maud Rise relative to the surrounding region are observed in all years, likely supported by flow‐topography interactions. The longer growing season in 2017–2018 also allowed for separation of distinct spring and fall bloom signals, the latter of which was primarily subsurface and associated with mixed‐layer deepening.
-
Abstract Background andAims The commodity purchase task is a simulated demand procedure that is easy and quick to complete (< 5 minutes) as well as adaptable for remote delivery and use with varied study populations. The purpose of this meta‐analysis was to synthesize research using the commodity purchase task with illicit substances to evaluate the magnitude of omnibus effects sizes and moderators of the correlation of demand indices with quantity–frequency (QF) and severity measures.
Design Random‐effects meta‐analyses and meta‐regressions involving studies with cross‐sectional correlational designs.
Setting and Participants Eleven studies, 10 outcomes and 2146 participants from two countries (USA and UK) published up to 1 October 2018.
Measurements Omnibus effect sizes (correlation coefficients) of five demand indices from the commodity purchase task [intensity (unconstrained consumption), elasticity (price sensitivity), Omax(maximum expenditure), Pmax(price at maximum expenditure) and breakpoint (first price of zero consumption)] with QF and severity measures. Meta‐regression models tested moderators of effect sizes (i.e. sample age and sex composition, commodity type and number of prices used in the commodity purchase task).
Findings Significant omnibus effect sizes were observed with QF and severity measures for intensity (
r = 0.32/0.28, QF/severity, respectively), elasticity (r = −0.14/−0.18), Omax(r = 0.30/0.29) and breakpoint (r = 0.17/0.22) values. Pmaxwas only significantly associated with severity measures (r = 0.15). The percentage of female participants and number of prices used in the purchase task significantly moderated Pmaxand breakpoint effect‐size estimates in that stronger associations were observed in samples with a greater percentage of women and in studies using tasks with more price points. Commodity type (cannabis versus cocaine) did not significantly moderate associations involving any demand index.Conclusions Behavioral economic demand as measured by the commodity purchase task is consistently correlated with measures of illicit substance use quantity–frequency and severity.