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Given the continuing miniaturization of underlying transistors, electronic functional units (circuits/systems) become increasingly susceptible to high-energy radiation, encountered in applications like space. Hence, redundancy is employed as a radiation hardening by design strategy to cope with faults of functional units used in such applications and to maintain their correct operation. Triple modular redundancy (TMR), which is a subset of N-modular redundancy (NMR), that can mask any single fault or a faulty functional unit has been widely used. However, compared to a simplex implementation a TMR implementation requires two additional functional units and a majority voting logic therefore a TMR implementation's area and power overheads are greater by over 200 %. This is burdensome for resource-constrained applications like space where low power and energy efficiency are important considerations. This paper presents a new redundancy strategy involving approximate computing called RESAC for error-tolerant applications such as digital image/video/audio processing, which is used in space systems. We evaluated the feasibility of RESAC for an image processing case study and the results confirm the usefulness. For implementation using a 28-nm CMOS technology, RESAC achieves reductions in area, delay, and power by 22.3 %, 15.3 %, and 24.9 % compared to TMR. Nonetheless, RESAC can address any NMR. • A novel redundancy scheme utilizing approximate computing called RESAC is proposed. • RESAC is suitable for use in inherently error-tolerant applications like digital signal processing. • A comparison between TMR and RESAC is performed for a digital image processing application. • RESAC produces images of good quality comparable to those produced by TMR. • For implementation, RESAC achieves 22.3 % reduced area, 15.3 % reduced delay, and 24.9 % reduced power compared to TMR. [ABSTRACT FROM AUTHOR]

Abstract: The electronic structure of Nd1−x Y x MnO3 (x=0–0.5) is studied using x-ray absorption near-edge structure (XANES) spectroscopy at the Mn K-edge along with the DFT-based LSDA+U and real space cluster calculations. The main edge of the spectra does not show any variation with doping. The pre-edge shows two distinct features which appear well-separated with doping. The intensity of the pre-edge decreases with doping. The theoretical XANES were calculated using real space multiple scattering methods which reproduces the entire experimental spectra at the main edge as well as the pre-edge. Density functional theory calculations are used to obtain the Mn 4p, Mn 3d and O 2p density of states. For x=0, the site-projected density of states at 1.7eV above Fermi energy shows a singular peak of unoccupied e g (spin-up) states which is hybridized Mn 4p and O 2p states. For x=0.5, this feature develops at a higher energy and is highly delocalized and overlaps with the 3d spin-down states which changes the pre-edge intensity. The Mn 4p DOS for both compositions, show considerable difference between the individual p x , p y and p z states. For x=0.5, there is a considerable change in the 4p orbital polarization suggesting changes in the Jahn–Teller effect with doping. [Copyright &y& Elsevier]

Highlights: [•] Decrease in the occupancy of Mn 3d orbitals with doping. [•] Greater splitting of the e g orbitals due to the increased Jahn–Teller distortion with doping. [•] Decrease in O 2p–Mn 3d charge transfer character with doping. [•] Increase in charge transfer energy and band gap with doping. [•] Calculations hint a subtle change from a charge transfer to Mott–Hubbard type insulator with doping. [ABSTRACT FROM AUTHOR]

This article presents a new asynchronous early output 3-input majority voter that is used to realize a high-speed, low power and less area occupying relative-timed asynchronous TMR implementation. The proposed majority voter is used to realize an asynchronous TMR implementation and it is compared with asynchronous TMR implementations realized using other asynchronous majority voters. The dual-rail code was used for data encoding and two kinds of four-phase handshaking were used for data communication. Compared to the existing implementations, we find that the proposed asynchronous majority voter leads to an efficient TMR implementation by simultaneously reducing the cycle time, silicon area, and average power dissipation by 25.1%, 7.5% and 7.8% respectively, on average. The implementations used a 32/28 nm CMOS process technology. [ABSTRACT FROM AUTHOR]