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Replication and Diversification
Published in Chris Hobbs, Embedded Software Development for Safety-Critical Systems, 2019
In the last few years, the tracks in the integrated circuits have narrowed. In 2005, track widths of 100 nm were typical; by 2010, this had reduced to 32 nm, and by 2018 tracks of 7 and 8 nm were being shipped. Because of this reduction, processors and memory chips have become more susceptible to cross-talk between tracks, thermal aging, electro-magnetic interference, and cosmiccosmic ray ray effects. Locked-step processing may again have a positive effect on the reliability aspect of the failure analysis, while having a negative effect on availability. It still will not, of course, catch either form of software bug.
Radiation Failure Mechanisms
Published in Judy Pecht, Michael Pecht, Long-Term Non-Operating Reliability of Electronic Products, 2019
The electrical failure modes caused by radiation dictate, in part, the choice of packaging materials. Radiation effects can be a serious obstacle to further rapid increases in VLSI densities, particularly in memory chips, which usually lead other microelectronics technologies in advanced development. Cosmic rays or high-energy particles (electrons, photons, muons, pions, neutrons, or alpha particles) can cause sudden random electrical failures in an ionization event — known as a single-event upset (SEU) or soft error — by passing through the microcircuit and adding enough charge to surpass the critical charge (100 fC) that represents a bit, thus temporarily changing the logic state. Single-event upsets are a consequence of the evolution of integrated circuits; increased density and speed and decreased power and cost per bit have been accomplished by decreasing both the cell size and the critical charge that represents a bit. As memory sizes increase and memory cell sizes shrink, the number of single-event upsets increases.
Challenges of designing a Tunnel Boring Machine (TBM) for development of underground structures on the Moon
Published in Daniele Peila, Giulia Viggiani, Tarcisio Celestino, Tunnels and Underground Cities: Engineering and Innovation meet Archaeology, Architecture and Art, 2019
J. Rostami, C. Dreyer, R. Duhme, B. Khorshidi
Radiation shielding: Radiation possesses a significant risk to human life in space from solar flares and galactic cosmic rays. Using regolith for radiation shielding has been recognized as a potential solution to this problem. Silberberg et al. (1985) recommend that lunar residents should spend most of the time protected by about 2 m of densely packed regolith, while at times of intense solar flares the regolith depth should be nearly doubled. This means that for long term use, the depth to the crown of >4 m would provide a safe living environment.
Assessment of health risk associated with natural gamma dose rate levels and isodose mapping of Jordan
Published in Radiation Effects and Defects in Solids, 2019
Ahmad Hussein Alomari, Muneer Aziz Saleh, Suhairul Hashim, Amal Alsayaheen
Exposure to ionising radiation is unavoidable for human beings living on earth (1). A combination of cosmic rays and terrestrial gamma radiation forms the part for natural radiation (2). Terrestrial radionuclides 238U, 232Th along with their decay products and non-decay series 40K, which are found in trace levels in all soil types, are the major sources of terrestrial gamma radiation (3). The high-energy radiation (also called cosmic rays) enters the earth’s atmosphere from the outer space. The contribution of cosmic ray is dependent on the latitude and altitude (4). UNSCEAR (3) reported that the value of gamma dose rate (GDR) at the sea level is 32 nGy h−1 for latitudes between 30° and 40°. Aircrew, frequent air travellers and mountain dwellers are exposed to higher doses of cosmic radiation.
Rutherford and the Cavendish Laboratory
Published in Journal of the Royal Society of New Zealand, 2021
With Geiger and Müller's improvements of the Geiger counter, individual cosmic rays could be detected and their arrival times determined very precisely. In 1929, Bothe and Kolhörster introduced the technique of coincidence counting for studying cosmic rays. They placed slabs of lead and gold up to 4 cm thick between the counters and measured the decrease in the number of coincidences when the absorber was introduced. The mass absorption coefficient agreed very closely with that of the atmospheric attenuation of the cosmic radiation. The experiment strongly suggested that the cosmic radiation had to consist of charged particles rather than γ-rays.