There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

News and social media platforms have implicated dietary supplements in the treatment and prevention of coronavirus disease 2019 (COVID-19). During this pandemic when information quickly evolves in the presence of contradicting messages and misinformation, the role of the pharmacist is essential. Here, we review theoretical mechanisms and evidence related to efficacy and safety of select supplements in the setting of COVID-19, including vitamin C, vitamin D, zinc, elderberry, and silver. Evidence evaluating these supplements in COVID-19 patients is lacking, and providers and patients should not rely on dietary supplements to prevent or treat COVID-19. Rather, reference to evidence-based guidelines should guide treatment decisions.

https://journals.sagepub.com/doi/pdf/10.1177/1060028020928052

Myth Busters: Dietary Supplements and COVID-19.

A current transformer (CT) is accurately modeled for representation of the CT saturation effects on digital protective relays. Simulation studies performed in the PSCAD/EMTDC platform are used to investigate the impacts of CT saturation on the current phasor estimation. A new algorithm is also proposed for detection and compensation of CT saturation effects, based on: a least error squares (LES) filter which estimates the phasor parameters of the CT secondary current; a novel saturation detection method which uses the output of the LES filter for saturation detection; and a new minimum estimation error tracking approach which enhances the precision of the phasor estimation. The proposed saturation detection/compensation algorithm is independent of the parameters of the CT, the burden, and the power system. The study results show that the proposed algorithm: 1) reconstructs the distorted current waveform, under dc and ac saturation conditions, with the required precision and speed and 2) performs satisfactorily under inductive burden and under deep and slight saturation conditions.

/pdf/compensation-of-the-current-transformer-saturation-effects-aokm4uygzk.pdf

Compensation of the Current-Transformer Saturation Effects for Digital Relays

In this paper, we present the first automated system-level analysis of multicore CPUs based on ARMv8 64-bit architecture (8-core, 28nm X-Gene 2 micro-server by AppliedMicro) when pushed to operate in scaled voltage conditions. We report detailed system-level effects including SDCs, corrected/uncorrected errors and application/system crashes. Our study reveals large voltage margins (that can be harnessed for energy savings) and also large $V_{min}$ variation among the 8 cores of the CPU chip, among 3 different chips (a nominal rated and two sigma chips), and among different benchmarks.Apart from the $V_{min}$ analysis we propose a new composite metric (severity) that aggregates the behavior of cores when undervolted and can support system operation and design protection decisions. Our undervolting characterization findings are the first reported analysis for an enterprise class 64-bit ARMv8 platform and we highlight key differences with previous studies on x86 platforms. We utilize the results of the system characterization along with performance counters information to measure the accuracy of prediction models for the behavior of benchmarks running in particular cores. Finally, we discuss how the detailed characterization and the prediction results can be effectively used to support design and system software decisions to harness voltage margins for energy efficiency while preserving operation correctness. Our findings show that, on average, 19.4% energy saving can be achieved without compromising the performance, while with 25% performance reduction, the energy saving raises to 38.8%.CCS CONCEPTS• Hardware → Power and energy → Power estimation and optimization; • Hardware → Robustness → Hardware reliability → Process, voltage and temperature variations

Harnessing voltage margins for energy efficiency in multicore CPUs

Residues from the processing of cassava roots (Manihot esculenta Crantz), or cassava peels, are evaluated as chemically modified adsorbents with H2O2, H2SO4, and NaOH, in the removal of metal ions Cd(II), Pb(II), and Cr(III) from contaminated water. Modified adsorbents were chemically characterized for their chemical composition and (point of zero charge), while adsorption tests determined the best conditions of pH, adsorbent mass, and contact time between adsorbent and adsorbate in the process of removal of the metal ions. Isotherms obtained from the preliminary results were linearized by Langmuir’s and Freudlich’s models. The thermodynamic parameters, such as , , and , were also evaluated. The modifying solutions proposed were effective in the modification of adsorbents and resulted in high capacity sorption materials. Equilibrium time between adsorbent and adsorbate for the solutions contaminated with metals is about 40 minutes. The Langmuir model adjusted to most results, indicating monolayers adsorption of Cd(II), Pb(II), and Cr(III). The values obtained for Langmuir show a higher adsorption capacity caused by chemical modifications, with values such as 19.54 mg Cd(II) per g of M. NaOH, 42.46 mg of Pb(II) per g of M. NaOH, and 43.97 mg of Cr(III) per g of M H2O2. Results showed that modified cassava peels are excellent adsorbent, renewable, high availability, and low-cost materials and a feasible alternative in the removal of metals in industries.

/pdf/chemical-modifications-of-cassava-peel-as-adsorbent-material-1oyvtwe2n9.pdf

Chemical Modifications of Cassava Peel as Adsorbent Material for Metals Ions from Wastewater

Tagu chi Design of Experiments (DOE) has been used in manufacturing, marketing, chemistry and biological experimentation. Orthogonal arrays, a part of DOE, has been successfully used in reducing test cases for software testing. Safety critical applications requ ire extensive testing as proof of robustness for certification. Component based software development put restriction on the test cases that can be generated for an end -to -end test. A sample component based safety critical flight control software has been considered as an example for experimenting with the use of DOE. The aim of the exercise is to generate a single test case, which can test the scheduled two dimensional table lookup completely for its data tabulation and interpolation algorithm. 2D tables of gains and filter time constants are commonly used in flight control systems. A comparison with random test case generation and Genetic Algorithm has been carried to compare the efficacy of the DOE process. It is seen that a single test case can be generat ed by just 38 experimentations using DOE as compared to 300 test cases for random and 600 test cases in case of Genetic Algorithm.

Optimized flight control component testing using taguchi design of experiments

Phase Noise optimization for RF oscillator using Design of Experiments (DOE) is presented. The constraint of keeping frequency deviation minimum is taken in to account by ANOVA and nominal-the-best approach of Taguchi methods. Phase Noise of the oscillator is improved by −3.6 dB with frequency deviation of 0.04 %. Power consumption is also reduced by 3.2 mW. 1

Optimizing Phase Noise of 2 GHz RF oscillator with minimum frequency deviation

This paper provides the enhancement of 22nm planar PMOS transistor technology through downscaling, design parameter simulation and optimization process. The scaled down device is optimized for its process parameter variability using Taguchi method. The aim is to find the best combination of fabrication parameters in order to achieve the target value of the threshold voltage (V th ). A combination of high permittivity material (high-k) and metal gate is utilized simultaneously in replacing the conventional SiO 2 /Poly-Si technology. For this, Titanium dioxide (TiO 2 ) was used as the high-k material and tungsten silicide (WSi x ) was used as the metal gate. The simulation results show that the optimal threshold voltage (V th ) of −0.289 V ± 12.7% is achieved in accordance to the ITRS 2012 specifications. This provides a benchmark towards the fabrication of 22 nm planar PMOS in future work.

Effect of process parameter variability on the threshold voltage of downscaled 22nm PMOS using taguchi method

Acceptable variations in the length of the valve stem, in a conventionally manufactured valve, give room to the possibility of the stem to buckle and get jammed in the guide. Salvaging such a situation is expensive and time consuming. The present paper addresses this problem by increasing the compliance of the valve stem by introducing holes in it. The desired elastic deformation along the length, however, causes transverse deformation, which needs to be minimized. The use of multiple holes helps achieve this. Taguchi Method based Design of Experiments using L25 orthogonal array has been used for performing the parametric design to arrive at the best settings of the 5 parameters. The optimal settings eliminate the buckling and thus make the operation of the valve stem robust against manufacturing variabilities.

Novel Design of Valve Stem to Eliminate Buckling

Optimizing Gain of an RF Amplifier using Design of Experiments (DOE), is presented. The constraints of keeping minimum deviations in both frequency and Noise Figure (NF) is taken in to account by ANOVA and nominal-the-best approach of Taguchi Methods. Gain of the amplifier is improved by 2.4 dB with frequency and NF deviations of 0% each.

Prakash R. Apte

Papers

Optimized flight control component testing using taguchi design of experiments

Optimizing Phase Noise of 2 GHz RF oscillator with minimum frequency deviation

Effect of process parameter variability on the threshold voltage of downscaled 22nm PMOS using taguchi method

Novel Design of Valve Stem to Eliminate Buckling

Optimizing Gain of 5 GHz RF amplifier keeping minimum deviation in center frequency and noise figure