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During the pandemic, the most significant reason for the deep concern for COVID-19 is that it spreads from individual to individual through contact or by staying close with the diseased individual. COVID-19 has been understood as an overall pandemic, and a couple of assessments is being performed using various numerical models. Machine Learning (ML) is commonly used in every field. Forecasting systems based on ML have shown their importance in interpreting perioperative effects to accelerate decision-making in the potential course of action. ML models have been used for long to define and prioritize adverse threat variables in several technology domains. To manage forecasting challenges, many prediction approaches have been used extensively. The paper shows the ability of ML models to estimate the amount of forthcoming COVID-19 victims that is now considered a serious threat to civilization. COVID-19 describes the comparative study on ML algorithms for predicting COVID-19, depicts the data to be predicted, and analyses the attributes of COVID-19 cases in different places. It gives an underlying benchmark to exhibit the capability of ML models for future examination.

Purpose This paper aims to propose a new assessment system module for handling the comprehensive answers written through the answer interface. Design/methodology/approach The working principle is under three major phases: Preliminary semantic processing: In the pre-processing work, the keywords are extracted for each answer given by the course instructor. In fact, this answer is actually considered as the key to evaluating the answers written by the e-learners. Keyword and semantic processing of e-learners for hierarchical clustering-based ontology construction: For each answer given by each student, the keywords and the semantic information are extracted and clustered (hierarchical clustering) using a new improved rider optimization algorithm known as Rider with Randomized Overtaker Update (RR-OU). Ontology matching evaluation: Once the ontology structures are completed, a new alignment procedure is used to find out the similarity between two different documents. Moreover, the objects defined in this work focuses on “how exactly the matching process is done for evaluating the document.” Finally, the e-learners are classified based on their grades. Findings On observing the outcomes, the proposed model shows less relative mean squared error measure when weights were (0.5, 0, 0.5), and it was 71.78% and 16.92% better than the error values attained for (0, 0.5, 0.5) and (0.5, 0.5, 0). On examining the outcomes, the values of error attained for (1, 0, 0) were found to be lower than the values when weights were (0, 0, 1) and (0, 1, 0). Here, the mean absolute error (MAE) measure for weight (1, 0, 0) was 33.99% and 51.52% better than the MAE value for weights (0, 0, 1) and (0, 1, 0). On analyzing the overall error analysis, the mean absolute percentage error of the implemented RR-OU model was 3.74% and 56.53% better than k-means and collaborative filtering + Onto + sequential pattern mining models, respectively. Originality/value This paper adopts the latest optimization algorithm called RR-OU for proposing a new assessment system module for handling the comprehensive answers written through the answer interface. To the best of the authors’ knowledge, this is the first work that uses RR-OU-based optimization for developing a new ontology alignment-based online assessment of e-learners.

Zinc oxide has emerged as an attractive material for various applications in electronics, optoelectronics, biomedical and sensing. The large excitonic binding energy of 60 meV at room temperature as compared to 25 meV of gallium nitride, an III-V compound makes ZnO an efficient light emitter in the ultraviolet (UV) spectral region and hence favourable for optoelectronic applications. The high conductivity and transparency of ZnO makes it important for applications like transparent conducting oxides (TCO) and thin-film transistors (TFT). In this paper, the optoelectronic, electronic and other properties that make ZnO attractive for a variety of applications are discussed. Various applications of ZnO thin film and its devices such as light-emitting diodes (LED), UV sensors, biosensors, photodetectors and TFT that have been described by various research groups are presented.

The paper report the fabrication and characterization of two different sets of bottom gate top contact ZnO thin film transistors (TFTs) using SiO2 and Al2O3 dielectric layers in an attempt to compare and contrast the effect of gate dielectrics on performance of the two devices. ZnO thin film and dielectric layers were deposited at room temperature by radio frequency (RF) sputtering method. The results were validated by those obtained using commercial software tool ATLAS and an analytical model reported by others. The ZnO TFT with Al2O3 dielectric exhibited superior electrical performance as compared to the ZnO TFT with SiO2 dielectric. The study also revealed that the performance of ZnO/Al2O3 based TFTs are far more consistent and reliable as compared to their ZnO/SiO2 counterpart.

There has been a significant global interest in the thin film transistor (TFT) due to its potential use in flat panel display. A great deal of interest in zinc oxide (ZnO) based TFT has been developed owing to its promising electronic and optoelectronic properties. The performance of a TFT is mainly measured by calculating the turn-on voltage, drain current on-to-off ratio ( I on /I off ) and channel mobility that depends on many factors like crystallanity of the active layer, quality of the insulator, and the quality of the interface between the different layers (semiconductor, insulator, and metallic contacts). All these factors further depend upon the growth and processing condition of different layers. This paper presents a short review that includes the factors affecting the performance of ZnO-based TFT and the methods to optimize them. The related work of reputed research groups are summarized and discussed systematically in the paper.

Pure and aluminum (Al) doped ZnO (Al:ZnO) nanorods (NRs) were deposited on silicon substrates by the hydrothermal method. The Al composition was kept at 2 % and 5 % for the Al:ZnO NR samples. The surface morphology and structural properties of the pure and Al:ZnO NRs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The XRD study revealed the hexagonal phase of the ZnO with (101), (002) and (100) peaks and it also revealed that the major orientation of ZnO NRs were along the (002) planes. The SEM micrographs showed perfectly grown ZnO NRs with hexagonal shaped tips. The electrical characterization of the pure and Al:ZnO NR thin film surface was done by scanning tunneling microscopy (STM). Local electron spectroscopy was conducted to measure the tunneling current with respect to the applied bias. The n-type behavior and bandgap of the pure and Al:ZnO NRs were confirmed from the dI/dV – V characteristics. These studies are of fundamental importance for the fabrication of pure and Al:ZnO NR based nanodevices.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.15305

The paper presents the results of our experimental investigation pertaining to tailoring of energy bandgap and other associated characteristics of undoped and Al doped ZnO (AZO) thin film by varying the atomic concentration of Al in ZnO. Thin films of ZnO and ZnO doped with Al (1, 3, and 5 atomic percent (at.%)) were deposited on silicon substrate for structural characterization and on glass substrate for optical characterization. The dependence of structural and optical properties of Al doped ZnO on the atomic concentration of Al added to ZnO has been reported. On the basis of the experimental results an empirical formula has been proposed to calculate the energy bandgap of AZO theoretically in the range of 1 to 5 at.% of Al. The study revealed that AZO films are composed of smaller and larger number of grains as compared to pure ZnO counterpart and density of the grains was found to increase as the Al concentration increased (from 1 to 5 at.%). The transmittance in the visible region was greater than 90% and found to increase with increasing Al concentration up to 5 at.%. The optical bandgap was found to increase initially with increase in atomic concentration of Al concentration up to 3 at.% and decrease thereafter with increasing concentration of Al.

Pure and Mg doped ZnO nanorod films were grown on p type silicon substrates by two step hydrothermal method. A solution of 60 mM concentration (by mixing zinc acetate with ethyl alcohol) is made for seed layer deposition. The main growth of pure ZnO and Mg [2 and 5 weight percent (wt%)] doped ZnO nanorod films were done after growing seed layer of undoped ZnO. The structural morphology of the pure and Mg doped ZnO nanorod (NR) films were characterized by X-ray diffraction and scanning electron microscopy. All the NRs were grown well on the ZnO seed layers and their top surface was hexagonal in shape. The electrical characterization of the Pd/ZnO and Pd/MgZnO NR Schottky contacts were studied by using microprobe arrangements. The values of ideality factor, barrier height and reverse saturation current were calculated from I to V characteristics of Schottky diodes. The study demonstrates that Pd/ZnO and Pd/MgZnO NR Schottky contacts fabricated by a simple and inexpensive method can be used as a substitute of conventional Schottky diodes for optoelectronic applications.

Zinc oxide (ZnO) thin films have been deposited on Si substrate and glass substrate using thermal evaporation, pulsed laser deposition (PLD) and radio-frequency (RF) sputtering methods. The structural, surface morphological, optical and electrical properties of ZnO thin films deposited by these three methods were investigated and compared systematically using x-ray diffractometer, atomic force microscopy, ellipsometric and current–voltage (I–V) measurement. The ZnO films deposited by RF sputtering method were highly oriented along the (002) plane. The ZnO films grown by thermal evaporation and PLD methods exhibited a polycrystalline nature. The surface roughness was found to be the least and the transparency in the visible region was the highest for the films grown by the RF sputtering method as compared to the films grown by the other two methods. The I–V characteristics reveal that the Pd:Au/ZnO (RF-sputtered) Schottky contact exhibited a better value of ideality factor, series resistance and barrier height as compared to the values obtained for Pd:Au/ZnO (thermally evaporated and pulse laser-deposited) Schottky contacts. The optical bandgap was found to be almost the same for the films grown by all three methods and was estimated to be around 3.2 eV.

The effect of target (Ti metal target and TiO 2 target) on Titanium Dioxide (TiO 2 ) thin films grown on ITO coated glass substrate by RF magnetron sputtering has been investigated. A comparative study of both the films was done in respect of crystalline structure, surface morphology and optical properties by using X-ray diffractometer (XRD), Atomic Force Microscopy (AFM) studies and ellipsometric measurements. The XRD results confirmed the crystalline structure and indicated that the deposited films have the intensities of anatase phase. The surface morphology and roughness values indicated that the film using Ti metal target has a smoother surface and densely packed with grains as compared to films obtained using TiO 2 target. A high transmission in the visible region, and direct band gap of 3.67 eV and 3.75 eV for films derived by using Ti metal and TiO 2 target respectively and indirect bandgap of 3.39 eV for the films derived from both the targets (Ti metal and TiO 2 target) were observed by the ellipsometric measurements.

This work reports structural and optical study of ZnO thin films grown over p-type silicon (Si) and glass substrates by RF magnetron sputtering technique. Surface morphological and optical properties of thin film have been studied using X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX), ellipsometry and photoluminescence (PL) spectroscopy. Strong diffraction peak (0 0 2) obtained from XRD spectra of ZnO thin film indicates a preferential growth of single crystalline thin film along the c-axis oriented phase of hexagonal wurtzite structure. Surface morphological feature reveals uniform growth of undoped ZnO thin film over the substrate. Different important microstructural parameters for the film such as grain size, lattice parameters, defect density, stress and strain have been obtained. Optical properties such as transmittance, reflectance, absorption coefficient, refractive index and dielectric constant for a spectral range of 300–800 nm have been evaluated. A good optical transmittance of 83–92% has been observed for visible region, and the optical bandgap of ZnO films was found to be 3.23 eV. Energy Loss Function (ELF) and photoluminescence (PL) spectra for ZnO thin film has also been analyzed and reported.

Ethanolic extract of Piper nigrum, Z ingiber officinale and A llium sativum revealed the presence of var i ous phytochemicals constituents; such as Alkaloids, Carbohydrates, glycosides, Tannins, flavones, Saponins etc. Piperine is characterizing compound present in fruits of P iper nigrum used as bioavailability enhancer. Gingerol is a measure pungent ingredien t of Z ingiber officinale , also has potent anti - oxidant activity. Allicin is an extract of Allium sativum has been presumed to be a very strong anti - oxidant. P resent investigations characterized by U.V. vis spectroscopy. The s pectrophotometric detection for piperine, gingerol, and allicin is carried out at the absorption maxima of 204 nm, 206 nm and 204 nm respectively.

ZnO thin films are deposited by single step and a two-step method on Si (100) substrates by using RF sputtering. The comparisons are based on structural, surface morphology and topography of ZnO thin films. XRD pattern of the ZnO film derived by two-step method exhibited single crystalline wurtzite structure. AFM results revealed the crystallite size and roughness of the ZnO thin film.

The present work involves the study of crystalline structure and surface morphology of Titanium Dioxide (TiO2) thin film deposited by RF magnetron sputtering. TiO2 thin film was grown on ITO coated glass substrate using Ti metal target. The XRD results revealed the crystalline structure and indicated that the deposited film had the intensities of metastable anatase phase. The surface morphology and its roughness values suggest that the film had smooth surface and densely packed with grains.

This study reports hydrothermally grown zinc oxide nanorod-based metal-semiconductor-metal ultraviolet detectors with palladium metal as the electrodes. The zinc oxide nanorods were deposited on glass substrates in two steps, seed layer deposition and growth of nanorods. The structural and optical properties of nanorods were examined using scanning electron microscopy and ultraviolet–vis spectroscopy, respectively. The scanning electron microscopy image showed that the growth of nanorods was uniform, and the ultraviolet–vis results indicate that the bandgap of zinc oxide nanorods was 3.23 eV. For metal-semiconductor-metal devices, interdigited metal electrodes with equal interelectrode spacing and a width of 0.3 mm were deposited above the zinc oxide nanorod thin films with a shadow mask using a thermal evaporation system. The current–voltage characteristics of the metal-semiconductor-metal detector were investigated and it showed a contrast ratio of approximately 2.10 and responsivity of approximately 0.199 A/W at 1.8 V. These results are expected to be beneficial to fabricating cheap and practical ultraviolet detection applications.

In this paper, we have primarily focused on the survey of power-delay performance of sub-threshold source coupled logic (STSCL) and STSCL-SFB (sub-threshold source coupled logic circuits with a source-follower buffer stage at output of each SCL gates) circuits. Here the comparisons have been drawn to derive the performance of STSCL and STSCL-SFB circuits in terms of PDP. The power dissipation has been kept same and the delay has been compared for both the circuits. Further, the analytical results measured in 180-nm CMOS technology showed an improvement of delay by a factor of 3 times. All the circuits have been designed in Cadence VIRTUOSO environment for simulation purpose.