Mitigating Intergranular Stress Corrosion Cracking in Age-Hardenable Al-Zn-Mg-Cu Alloys

Metallurgical and Materials Transactions A - This article reports an attempt to develop high-strength aluminum alloys of 7xxx series resistant to intergranular stress corrosion cracking (SCC). A...     

Organic acid leaching of base metals from copper granulated slag and evaluation of mechanism

A hydrometallurgical method is discussed to selectively extract base metals such as copper, cobalt, nickel and iron from the copper granulated slag (0.53% Cu) at atmospheric pressure. It involves first-stage leaching of slag with organic (citric acid) to selectively recover cobalt, nickel and iron. The residue containing high copper was subjected to second-stage leaching with inorganic (sulphuric) acid. Leaching parameters such as acid concentration, pulp density, temperature and time were optimised to extract metals from the granulated slag. A maximum recovery of 4.47% Cu, 88.3% Co, 95% Ni and 93.8% Fe were obtained in first-stage leaching with 2?N citric acid at room temperature using 10% pulp density (w/v) in 8–9?h. On subjecting the leach residue to the second-stage leaching with 2?M sulphuric acid, 66–72% Cu was recovered in 4?h. The kinetics of the metal leaching from the slag was established by the XRD and SEM–EDAX studies of the residues.     

CompactChain: an efficient stateless chain for UTXO-model blockchain

In this work, we propose a stateless blockchain called CompactChain, which compacts the entire state of the UTXO (Unspent Transaction Output) based blockchain systems into two RSA accumulators. The first accumulator is called Transaction Output (TXO) commitment which represents the TXO set. The second one is called Spent Transaction Output (STXO) commitment which represents the STXO set. In this work, we discuss three algorithms: (i) To update the TXO and STXO commitments by the miner. The miner also provides the proofs for the correctness of the updated commitments; (ii) To prove the transaction’s validity by providing a membership witness in TXO commitment and non-membership witness against STXO commitment for a coin being spent by a user; (iii) To update the witness for the coin that is not yet spent; The experimental results evaluate the performance of the CompactChain in terms of time taken by a miner to update the commitments and time taken by a validator to verify the commitments and validate the transactions. We compare the performance of CompactChain with the existing state-of-the-art works on stateless blockchains. CompactChain shows a reduction in commitments update complexity and transaction witness size which inturn reduces the mempool size and propagation latency without compromising the system throughput (Transactions per second (TPS)).     

Gate replacement with PMOS stacking for leakage reduction in VLSI circuits

Scaling down the circuits of complementary metal oxide semiconductor increases the leakage current. Input vector control is an extremely popular method for controlling leakage without using any technological modification. However, it is less effective for larger logic depth circuits. Our study proposes a Worst Leakage State (WLS) free‐node algorithm based on gate replacement technique, in which, when the logic gate of a given circuit goes into WLS, it is replaced by a suitable variant of the gate which in turn reduces the leakage current in an idle mode of the circuit at the same input vector. These variants minimize leakage under WLS conditions. For replacement purpose, four variants (V1–V4) of a two‐input NAND gate are proposed. This technique is applied on different circuits and some benchmark circuits such as ISCAS'85 (C17) and ITC'99 (B01, B02 and B06) (total of 10 circuits), according to the proposed algorithm with variants V1–V4. The average total power is reduced to 15.04%, 15.04%, 35.7% and 31.5%, and the leakage current is reduced to 42.96%, 42.96%, 84.25% and 84.52%, respectively, for variants V1–V4. The average delay is decreased by 16.03% in V1 and V2 variants and increased by 7.74% and 13.16% for variants V3 and V4, respectively, as compared with the results of conventional circuits at 45‐nm Berkeley Predictive Technology Model technology. Copyright © 2015 John Wiley & Sons, Ltd.     

Robust control of discrete minimum and non-minimum phase systems via data-driven virtual reference feedback tuning and IMC

In this paper, we develop a novel robust control approach for discrete minimum and non-minimum phase systems via a combined data-driven virtual reference feedback tuning ($\text{VRFT}$) and internal model control (IMC) scheme. The first step in the conventional $\text{VRFT}$ method controller design is the selection of the closed-loop reference model ($M\left(z\right)$), and $M\left(z\right)$ selection is still an open problem. The integration of the $\mathrm{IMC}$ scheme and the VRFT method provides the advantage of flexibility in controller design due to the incorporation of the $\mathrm{IMC}$ filter. As a result, the proposed design method begins with the selection of $M\left(z\right)$ and $\mathrm{IMC}$ filter. Unlike the standard $\text{VRFT}$ method, the proposed combined $\text{VRFT}$ and $\mathrm{IMC}$ design approach has the unique feature of taking into account a robustness property of dynamics, namely, maximum sensitivity ($M_{\mathrm{s}}$) as the design specification for the $M\left(z\right)$ and IMC filter selection. Moreover, the proposed approach includes a robustness specification that resolves the trade-off between performance and robustness in real-time controller design. Furthermore, the robustness guarantee with plant uncertainties and controller fragility is elucidated. The proposed approach is validated using numerical simulations and experimental validation through the temperature control process. Compared to conventional $\text{VRFT}$ controllers, experimental and simulation results show that the proposed controllers have less tracking error, minimize control effort, and improve robustness.