Prakash R. Apte

Bio: Prakash R. Apte is an academic researcher from Indian Institute of Technology Bombay. The author has contributed to research in topics: Taguchi methods & Threshold voltage. The author has an hindex of 7, co-authored 48 publications receiving 166 citations. Previous affiliations of Prakash R. Apte include Indian Institutes of Technology & Datta Meghe College of Engineering.

Generating Test Cases with 100-Percent Requirements Coverage Using Design of Experiments

Abstract: Model-based testing has become a de facto methodology for flight-control law verification and validation today. The recent flight-control programs of commercial aircraft like the Boeing 747-8 and Airbus A350 XWB are verified and validated using model-based test methods. These projects are long-timeframe projects, and so modification and improvements in control laws are predictable. Test cases have to be generated for these modified segments, and the timeframes get compressed as the project approaches the certification phase. Hence, there is a need for test-case automation. Four methods of test-case automation are compared here for their efficacy in ensuring 100% requirements coverage and the time taken to generate such tests. A methodology of defining control theoretic requirements coverage is used here to generate the test cases. Random, simulated annealing, genetic algorithm, and design-of-experiments methods are used to generate the optimized set of test cases. The design of experiments is a method use...

Step height measurement of surface-functionalized micro-machined micro-cantilever by scanning white light interferometry

Abstract: Micro-cantilever arrays with different dimensions are fabricated by micro-machining technique onto a silicon substrate. These sputtered gold-coated micro-cantilevers were later surface-functionalized. Scanning electron microscopy, atomic force microscopy (AFM), and optical diffraction using a laser source are employed to characterize the morphology and image measurement of the micro-cantilever arrays. The spatial resolution produced in the proposed image measurement method is approaching 1 μm, and the repeatable precision is nanometer confirmable. Compared with conventional AFM and SPM measurement techniques, the proposed method has demonstrated sufficient flexibility, repeatability, and reliability. The experimental results have been analyzed and presented in this paper for microelectromechanical system (MEMS) micro-cantilevers. The scanning white light interferometry-based two-point high-resolution optical method is presented for characterizing micro-cantilevers and other MEMS micro-structures. In this letter, we investigate the micro-structure fabrication and image measurement of length, width, and step height of micro-cantilever arrays fabricated using bulk micro-machining technique onto a silicon substrate.

Growth and Characterization of High-Quality Dielectric Sputtered Zinc Oxide Films from the First Principle

Abstract: In this article, we investigate the effect of thermal treatment on a piezoelectric material, zinc oxide, which has found numerous applications in sensors and actuators. Even though the exact mechanisms rendering electrical properties are less known, we suspect that the thermal treatments are responsible for improvement of electrical characteristics of the deposited thin films. We establish that the thermal agitation is responsible for improvement of orders of magnitude in electrical characteristics of sputtered ZnO thin films. The surface quality of the thin films deposited is process dependent. ZnO films were deposited using a dielectric sputtering method, on oxidized silicon 100 n-type wafers. Further, these films were thermally annealed in oxygen ambient at 600 °C in a tube furnace with 2 mL/min pressure. It is observed that, after thermal annealing, the quality of the films is improved by orders of magnitude. The luminance, crystalline quality, and surface morphology of these thin films was measured with atomic force microscopy, scanning electron microscopy with BSD detector (BSD-SEM), and Fourier transform infrared spectroscopy (FTIR). The results infer that the film’s surface is very smooth and dense. The surface roughness is improved by 1.3149 nm from 7.882 nm prior to thermal annealing to post-annealing surface roughness with 6.5671 nm. Post-thermal annealing process reveals average grain size was 50 nanometers; the surface roughness is reduced to 6.5671 nm. A significant improvement in electrical current-voltage characteristics was recorded with I-V curve. It is suspected to be due to substantial enhancement in electrical conductivity as a result of thermal treatment and improved spectral response recorded a FTIR peak shift of 1 wave number in total. The FTIR peak shift is suspected to be due to evaporation and reduction in oxygen vacancies due to thermal annealing process. The post-annealed ZnO films will be used for actuation in the future.

Optimum design of SU-8 based accelerometer with reduced cross axis sensitivity

Abstract: The work presented here shows a new design for SU8 based piezoresistive accelerometer, where SU8/carbon black is used as piezoresistors. The accelerometer structure is optimized to generate maximum bending stress at the base of the beams. The structure is inherently temperature insensitive. The design of proof mass is such that the sensitivity to cross axis acceleration is kept within a limit of 4%.

Experimental evaluation of current transformer performance under saturation

Abstract: Current transformers form an integral part of protective systems. Ideal current transformers (CTs) are expected to reproduce the primary current faithfully on the secondary side. Often, during fault conditions an important component of current is exponentially decaying DC offset current. Under such conditions the CT saturates, and hence it cannot reproduce the primary current faithfully. This paper deals with experimental methods for determining CT performance under saturation. A laboratory setup has been developed to observe CT response under steady state and fault conditions. Thus, it is now possible to experimentally evaluate the CT performance under fault conditions

I and i

Abstract: 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 …

Myth Busters: Dietary Supplements and COVID-19.

Abstract: 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.

Compensation of the Current-Transformer Saturation Effects for Digital Relays

Abstract: 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.

Harnessing voltage margins for energy efficiency in multicore CPUs

Abstract: 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

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

Abstract: 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.