ECC Memory for Fault Tolerant RISC-V Processors

Numerous processor cores based on the popular RISC-V Instruction Set Architecture have been developed in the past few years and are freely available. The same applies for RISC-V ecosystems that allow to implement System-on-Chips with RISC-V processors on ASICs or FPGAs. However, so far only very little concepts and implementations for fault tolerant RISC-V processors are existing. This inhibits the use of RISC-V for safety-critical applications (as in the automotive domain) or within radiation environments (as in the aerospace domain). This work enhances the existing implementations Rocket and BOOM with a generic Error Correction Code (ECC) protected memory as a first step towards fault tolerance. The impact of the ECC additions on performance and resource utilization are discussed

A comparative survey of open-source application-class RISC-V processor implementations

Revision notice: This version does not contain CVA6 SPEC CPU2017 scores. There is an updated version available with additional CVA6 SPEC CPU2017 scores: https://doi.org/10.24355/dbbs.084-202105101615-

A comparative survey of open-source application-class RISC-V processor implementations

The numerous emerging implementations of RISC-V processors and frameworks underline the success of this Instruction Set Architecture (ISA) specification. The free and open source character of many implementations facilitates their adoption in academic and commercial projects. As yet it is not easy to say which implementation fits best for a system with given requirements such as processing performance or power consumption. With varying backgrounds and histories, the developed RISC-V processors are very different from each other. Comparisons are difficult, because results are reported for arbitrary technologies and configuration settings. Scaling factors are used to draw comparisons, but this gives only rough estimates. In order to give more substantiated results, this paper compares the most prominent open-source application-class RISC-V projects by running identical benchmarks on identical platforms with defined configuration settings. The Rocket, BOOM, CVA6, and SHAKTI C-Class implementations are evaluated for processing performance, area and resource utilization, power consumption as well as efficiency. Results are presented for the Xilinx Virtex UltraScale+ family and GlobalFoundries 22FDX ASIC technology

Autonomous on-board data processing and instrument calibration software for the Polarimetric and Helioseismic Imager on-board the Solar Orbiter mission

This is an open access article. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.A frequent problem arising for deep space missions is the discrepancy between the amount of data desired to be transmitted to the ground and the available telemetry bandwidth. A part of these data consists of scientific observations, being complemented by calibration data to help remove instrumental effects. We present our solution for this discrepancy, implemented for the Polarimetric and Helioseismic Imager on-board the Solar Orbiter mission, the first solar spectropolarimeter in deep space. We implemented an on-board data reduction system that processes calibration data, applies them to the raw science observables, and derives science-ready physical parameters. This process reduces the raw data for a single measurement from 24 images to five, thus reducing the amount of downlinked data, and in addition, renders the transmission of the calibration data unnecessary. Both these on-board actions are completed autonomously. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.This work was carried out in the framework of the International Max Planck Research School for Solar System Science at the Max Planck Institute for Solar System Research. Solar Orbiter is a mission led by the European Space Agency with contribution from the National Aeronautics and Space Administration (NASA). The Polarimetric and Helioseismic Imager instrument is supported by the German Aerospace Center (DLR) under grant Nos. 50 OT 1201 and 50 OT 1901. The Spanish contribution has been partly funded by the Spanish Research Agency under projects under grant Nos. ESP2016-77548-C5 and RTI2018-096886-B-C5, partially including European FEDER funds. IAA-CSIC members acknowledge and funds from the Spanish Ministry of Science and Innovation “Centro de Excelencia Severo Ochoa” Program under grant No. SEV-2017-0709. The solar data used in the tests are the courtesy of NASA/SDO HMI science team. Parts of the work shown in this paper have been introduced at the SPIE Astronomical Telescopes + Instrumentation conference.42 EditorialPeer reviewe

Cyanide leaching of Au/CeO2: highly active gold clusters for 1,3-butadiene hydrogenation

Ceria-supported gold catalysts before and after leaching by NaCN were investigated by X-ray absorption spectroscopy at the Au LIII edge. After gold leaching, isolated gold cations remain in close interaction with the support. These ions form an ideal precursor to very small clusters of a few gold atoms upon reduction. The resulting gold clusters exhibit a very high intrinsic activity in the hydrogenation of 1,3-butadiene, which is at least one order of magnitude higher than that of the nanometre-sized gold particles in the non-leached parent catalyst. These findings point to a very strong structure sensitivity of the gold-catalyzed hydrogenation of dienes

Ethanol dehydrogenation by gold catalysts: The effect of the gold particle size and the presence of oxygen

A range of silica-supported gold nanoparticle catalysts have been synthesized on various silica supports. The particle size was varied between 1.7 and 15 nm by varying the support (ordered mesoporous silicas, silicas with and without aluminium impurities) and the gold loading procedure. A strong influence of the gold particle size on the non-oxidative dehydrogenation of ethanol is noted: gold nanoparticles of about 6 nm show a much higher activity than smaller or larger particles. This optimal catalytic activity is attributed to the existence of surface steps with a suitable geometry for the removal of ß-H atoms from adsorbed ethoxide. Such stepped sites are expected to be present with maximum density for intermediate particle size. In the presence of oxygen, the rate for dehydrogenation is much higher because of the presence of an adsorbed oxygen species, but the selectivity becomes lower as combustion starts to contribute. The intrinsic activity is constant up to about 7 nm and then increases for larger particles. The larger gold nanoparticles may contain strongly adsorbed oxygen adatoms, which are much scarcer on smaller gold particles. Infrared spectroscopy shows that, already at room temperature, adsorbed ethoxide reacts with molecular oxygen, whereas C-H bond cleavage to produce acetaldehyde requires at least a temperature of 75 °C. The reaction rate is first order with respect to ethanol in both cases. © 2009 Elsevier B.V. All rights reserved

Selective oxidation of ethanol to acetaldehyde by Au−Ir catalysts

The use of Ir as a reactive transition metal for O2 activation to facilitate the selective oxidation of ethanol to acetaldehyde is explored. Co-impregnation of the chlorides of Au and Ir on SiO2 followed by reduction afforded small bimetallic nanoparticles with a varying Au/Ir ratio. All of the nanoparticle catalysts including the monometallic Au and Ir end members have sizes in the range of 2–3 nm. Infrared spectroscopy of adsorbed CO on the reduced catalysts evidences the formation of alloyed nanoparticles. After oxidation at room temperature and at 200 °C, the Ir surface atoms are oxidized. No synergy between Au and Ir is observed in CO oxidation. Au lowers the CO oxidation activity of the pure Ir catalyst, suggesting the presence of surface Au atoms in the mildly oxidized Au–Ir bimetallic catalysts. At higher oxidation temperatures, viz. 350 and 500 °C, bulk oxidation of Ir occurs. While pure Ir nanoparticles sinter upon oxidation at elevated temperatures (350–500 °C), the presence of Au significantly retards this agglomeration of the nanoparticles. At these elevated temperatures, an intimate mixture of reduced Au and IrOx is formed. The Au–Ir nanoparticles display enhanced activity in ethanol oxidation to acetaldehyde, outperforming their monometallic counterparts, with only minimum loss of C2-oxygenates selectivity compared to the pure Au nanoparticle catalyst. The maximum activity is obtained for a Au–Ir3 composition. The present results can be explained by a model involving an intimate contact between Au sites for (dissociative) ethanol adsorption and Ir sites covered by O adatoms which catalyze C–H bond cleavage to yield acetaldehyde

Interactive retention index database for compound identification in temperature-programmed capillary gas chromatography

A procedure is described and evaluated that allows the calculation of linear temperature-programmed retention indices from accurate Kováts retention indices on a given stationary phase and their temperature variation coefficients. The influence of experimental factors such as column film thickness, phase ratio and variation of Kováts retention indices, column dead time and carrier gas flow-rates are examined. The calculation accuracies are = 0.5 retention index units in most instances. The applicability and limitations of the procedure are discussed