Indian Journal of Pure & Applied Physics (IJPAP)

Precipitable Water Vapour Retrieval Modelling Using Indian Regional Navigation Satellite System (IRNSS) Observations over Dehradun

Ashutosh Srivastava — Tue, 03 Dec 2024 00:00:00 +0530

In the present work, a maiden attempt has been made to derive precipitable water vapour (PWV) using IRNSS datasets. A least square differential correction approach is used in modelling to process datasets. PWV is estimated for different days of January, April, July, and November of the year 2019 to observe its variation over different seasons. Meteorological datasets used in the estimation of zenith hydrostatic delay (ZHD) and weighted mean temperature estimation are taken from the National Centers for Environmental Prediction (NCEP) at the location. The obtained PWV values are validated with GPS-derived PWV and Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis datasets. The results show that PWV derived using IRNSS datasets are close to the other reference values. The difference of 3 mm to 7 mm was observed if compared with GPS-derived PWV and MERRA PWV values. Since each satellite signal is available at all times, PWV is estimated using the individual satellite data and combined data from all the IRNSS satellites. As the IRNSS constellation includes both geostationary and geosynchronous satellites, it is observed that PWV estimated using geostationary satellite datasets is close to the reference datasets having a difference of 3 to 5 mm. However, estimated PWV using geosynchronous satellite data have more variation with differences within 3 to 7 mm. Combined data from all the satellites was also used to derive the PWV which has a difference of close to 5 mm in all the cases. The obtained PWV values using IRNSS data show a good correlation with GPS PWV and MERRA PWV values and provide a good estimate of PWV.

Thermal Conductivity Enhancement of Phase Change Materials Using Metal Wire Woven Porous Structures for Thermal Energy Storage

Tue, 03 Dec 2024 00:00:00 +0530

In the present work, the thermal conductivity of paraffin wax has been increased using low-cost and lightweight aluminium wire metal foam structures. The designed metal wire foam structures have uniform-sized circular pores forming a convective spring-like network for faster heat transfer. The paraffin wax can easily infiltrate the designed wire woven foam structures even at a lower porosity (~75 vol %). The latent heat thermal energy storage (LHTES) systems which can store up to 500 kJ of thermal energy have been designed using the PCM-wire-woven metal foam composite material. The heating of these composites is carried out both in convection and conduction modes, and their effect has been studied. The effect of using a polymer (acrylic), and a galvanized iron (GI) sheet to encapsulate PCM-metal wire foam composites is also evaluated. Increasing the pore diameters in the wire woven structures, and its effect on the thermal efficiencies of the LHTES system is calculated. The thermal efficiency of the LHTES ranged from 67 to 92 % using an acrylic sheet, and 72 to 77 % using the GI sheet. The heat extraction using cold water could be continued for 8-9 cycles in acrylic, and 5-6 cycles in GI sheet capsulation.

Advancing Terahertz Connectivity of Innovative Design of a Directional Cross-Dipole Antenna with Conformal Graphene-Based Reconfigurable Intelligent Surface

Tue, 03 Dec 2024 00:00:00 +0530

In contemporary systems, there is a growing emphasis on harnessing tunable terahertz (THz) waves to advance wireless communication swiftly. Furthermore, reconfigurable intelligent surfaces (RISs) have noticeably enhanced the performance of THz components and devices that enabling them to control electromagnetic waves effectively. Within the domain of wireless systems operating within the THz frequency range, a demand has arisen for adjustable directional antennas. This paper presents a novel approach that suggests a solution involving a customizable directional antenna design which utilizing a cross-dipole configuration with a central graphene-based dipole element. The electrical conductivity of these dipole elements can be adjusted independently by applying a bias voltage via the graphene's chemical potential. The concept of employing a graphene-based Reconfigurable Intelligent Surface (RIS) to actively manipulate Terahertz (THz) waves. By carefully engineering the reflection characteristics of the individual unit cells, the overall system performance can be enhanced. The proposed conformal RIS design comprises a repetitive arrangement of rectangular graphene meta-atoms positioned on a silicon substrate grounded with metal. The paper also provides a model featuring an equivalent circuit for the RIS design and its solution. Furthermore, an implementation of tunable surfaces featuring the conformal graphene-based RIS. It is developed to be placed beneath the
cross-dipole antenna at an appropriate distance. This setup enables the control of radiated patterns through a reconfigurable process that involves changing the states of the meta-atoms to achieve specific codes with corresponding patterns. The antenna can achieve various gains that ranging from 8.3 to 9.3 dBi. The results of this study demonstrate the promising potential of the proposed antenna structure for efficient and intelligent THz wireless communications.

A Crystal Growth and Characterization of an Efficient Nonlinear Optical Material: -Glycine Crystal

Dr. S. Gracelin Juliana, Dr. P. SATHISHKUMAR, Dr. S. C. Vella Durai — Tue, 03 Dec 2024 00:00:00 +0530

In an aqueous solution of ferrous chloride, g - Glycine Crystal (g-GC), an efficient nonlinear optical (NLO) material, was created. AR grade glycine and ferrous chloride in a molar ratio of 1: 0.5 were employed to grow the title sample. The lattice properties of g-GC were determined using a single crystal X-ray diffraction method. High transmittance in the visible area and a UV-visible spectrum make g-GC excellent for optical applications. Using a Nd:YAG laser, the produced crystal's LDT value was ascertained. The crystal's hardness was assessed using the Vickers test, and other mechanical properties were determined. The electrical properties of g-GC were examined by measuring the dielectric constant and dielectric loss at various frequencies, and temperatures. Using TG/DTA tests to gauge the sample's thermal stability, the functional groups of the g-GC were identified by FTIR analysis. The material also underwent SHG and LDT testing.

Solar Cells on the Base of Isotype Heterojunction Black Silicon - Crystalline Silicon

FERDINAND GASPARYAN, Vladimir Gasparian — Tue, 03 Dec 2024 00:00:00 +0530

Simulations of the short-circuit current, open-circuit voltage, absorption coefficient, fill factor and power conversion efficiency of a p-type black silicon/p-type crystalline silicon isotype heterojunction were carried out. Such a heterojunction is part of a complex tandem 2T solar cell NiO – Perovskite – TiO₂ – black Si – crystalline Si. The expression used for the current-voltage characteristic of a heterojunction takes into account the electrical, optical and geometric parameters of both crystalline and black silicon. Analytical expressions were obtained for the absorption coefficients for both crystalline (for the wavelength range 700-1100 nm) and black silicon (for the wavelength range 300-700 nm). The best model data obtained for a short-circuit current density of ~31 mA/cm² and an open-circuit voltage of ~634 mV are obtained for the wavelength range 500-800 nm and are in good agreement with the results of previous numerical and experimental data for solar cells of similar composition and size. The calculations show the potential possibility of using black silicon in the design of tandem solar cells. The novelty of this work is the demonstration of the possibility of using thin layers of black silicon to convers solar energy. This material provides good absorption of photons with energy >1.4 eV. In combination with the crystalline silicon, black silicon can broaden the absorption spectrum of irradiation, thereby increasing the power conversion efficiency of the tandem solar cells.

Dr. The calcination temperature dependent structural and optical behaviour of ZnMnO3-Δ nanocrystallines

Tanuja Kumari, Sunita Dahiya, Rajesh Sharma — Tue, 03 Dec 2024 00:00:00 +0530

The materialistic particles have remarkable technological application at size of nano scale (1-100 nm). The metal such as zinc and manganese have enhanced properties in field of Optical, Magnetic, Electrical and Biogenic field because of valence d-orbital electrons with great efficiency. In present work,the researcher synthesized pure ZnO and 10% Mn doped ZnO nano particulates via microwave irradiated chemical co-precipitation protocols andthen as synthesized samples were calcined at 200, 400 & 600 ^oC for 2hrs. The powdered sample of pure and ZnO and Mn doped ZnO were examined through XRD, FTIR, FESEM and HRTEM characterization tools. The XRD results indicates that wurtzite crystalline were in formation with crystallite size increase with increase of calcinations temperature. The intensity of absorption was increases with increase of calcinations temperature 200, 400 & 600 ^oC for 2hrs.The IR absorption peak at about 403, 404, 413cm^-1& 638, 658, 669 cm^-1 were assigned to O-Zn-O and O-Mn-O vibration of ZnO & MnO₂ respectively. The morphological studies of particles were examined by electron microscopic tools FESEM and HRTEM. The magnified images of MnO/ZnO sample indicates that single phase hexagonal structure was formed and morphology of ZnO pure particles were spherical whereas, MnO/ZnO calcined at 600^oC 2hrs were 2D nanosheet occurrence in nature. The photoluminescence (PL) study of various samples concluded that newer material has primary excitation energy level at about 303, 305, 307nm and secondary exciton energy level 471, 474, 477nm whereas, the emissive transition occurred at position 661, 665, 668nm for 10% Mn doped ZnO crystalline calcined at 200, 400 & 600 ^oC for 2 hrs respectively. The newer calcined materials have remarkable properties in field of optoelectronics as the material have optical band gap at about 1.8 eVto 1.90 eV respectively and may have provoked application in field of herbicide and bactericidal applications in presence of sunlight.

Electrical and Dielectric Properties of PbO.Bi2O3.SiO2 Glasse

Rajni Bala, Ashish Agarwal, Sujata Sanghi — Tue, 03 Dec 2024 00:00:00 +0530

A series of lead-bismuth silicate glasses have been made via classical melt-quench route in the compositional range 20PbO∙(80-x)Bi₂O₃∙xSiO₂ (where, x = 10, 20, 30, and 40mol%). Impedance spectroscopy was used to collect temperature-dependent conductivity data for the glass series in the range of frequency 10Hz-7MHz and at temperatures ranging from
473K-703K. The non-Debye type nature of relaxing ions is shown by complex impedance plots. From experimental impedance data, DC conductivity; σ_dc, power law exponent; s, activation energy for dc conduction; E_dc, relaxation time; t_M_ꞌꞌ, activation energy for relaxation; E_τ were extracted. The dc conductivity decreased with an increase in SiO₂content and was found to follow Arrhenius law. A close agreement in the values of activation energies determined from different formalisms suggested that during both the conduction and relaxation processes, the charge carriers must cross the similar height energy barrier.

Modification in Magnetic properties with Copper Oxide dopant concentration in NiCuO2-δ Nano crystalline

Sheela Sheela, Rajesh Sharma, Sunita Dahiya — Tue, 03 Dec 2024 00:00:00 +0530

In present work, the Copper doped Nickel Oxide nanoparticles with molar concentrations (0%, 5%, 10% & 20%) were synthesized by microwave irradiated chemical co precipitation protocol and thereafter, calcination, the required
nano-crystalline materials samples were examined through various techniques in order to make a comparative analysis of the magnetic behavior of pure Nickel Oxide nano-crystalline with various Copper doped Nickel Oxide nano-crystalline materials. The structural outcomes from X-Ray Diffractometer (XRD) tool and Fourier Transform Infar Red (FTIR) technique shows that FCC crystalline structure of NiO occurs. The crystallite size was determined using Debye Scherer formula and average crystallite size was 36.35nm for un-doped NiO nano particles whereas on addition the content of doping the crystallite size varies from 37.38nm for Cu 5%, 36.10nm for Cu 10% and 28.07nm for Cu 20% at when calcined at 600 °C temperature for 2 hours respectively. The IR spectrum peaks at positions 478 cm-1were attributed by O-Ni-O vibration whereas peak at 567 cm-1and 687cm-1 were assigned to O-Cu-O vibrations of CuO & Cu2O crystalline respectively.VSM results of various calcined samples with different dopant concentrations reveals that the behaviors of nanoparticles were ferromagnetic in nature with small hysteresis loss. However, the remarkable changes were noticed in saturated magnetization intensity with Cu2+ ion concentration in NiO lattice structure. The Cu 10% concentration doped NiO nanostructure materials were recommended as key materials for electromagnetic formation for MRI equipment applications with high range of applied magnetic field.

Parametric Study of Via Shorting-pin Loaded Novel Shape Miniaturized Monopole Antenna for Body Implantable Applications

Ambresh P A, Amit Birwal — Tue, 03 Dec 2024 00:00:00 +0530

This paper deals with the parametric study of novel monopole antenna with circular ring shape in body-implantable applications. The miniaturized antenna is placed inside skin phantom tissue of human body that has a dimension of 5x5x0.125mm³. A single wide band is observed for this implantable antenna design with better return loss. The suggested antenna uses a mid-band frequency range of 1520–1693 MHz, ISM band ranging from 433.1–434.8 MHz, and Medical Implanted Communication Service of 402–405MHz. The antenna exhibited compact size and fabricated on RT Duriod 5880 substrate with the property of flexible/ bendable in nature. A significant compact design of the antenna is achieved by using similar dimension of rectangular arms on the circular shape ring patch.The compact dimensions, reduced ground plane, and bandwidths of the suggested antenna are its salient characteristics with the obtained bandwidths are of 500MHz, 550MHz, 650MHz, 585MHz, 690MHz, 652MHz and 740MHz and acceptable gain levels in comparison with other implanted antennas working in the ISM band. The simulated realized gain values are -13.3dBi, -22.1dBi and -18.4dBi respectively.

Artificial Intelligence Based Investigation for the Impact of High PM2.5 Concentration on Cloud Parameters over the Polluted Central IGP location, Kanpur

Tue, 03 Dec 2024 00:00:00 +0530

This research focuses on using artificial neural network (ANN) models to assess daily surface PM_2.5concentrations by incorporating aerosol optical depth (AOD) and cloud parameters from the Moderate Resolution Imaging Spectroradiometer (MODIS), along with meteorological data, for the period from January 2017 to December 2021 over Kanpur. For this exercise, three ANN models were utilized: ANN1 (1 Layer, 14 Neurons), ANN2 (2 Layers, 14, 28 Neurons), and ANN3
(1 Layer, 14, 28, 14 Neurons). Statistical tests such as FAC2, MGE, NMB, MAPE, RMSE, R, and COE were conducted to validate the models. Initial results show that the ANN1 performed the best. The study also examined spatial and temporal changes to observe variations in PM_2.5, AOD, and various cloud properties, including water vapor (WV), cloud effective radius (CER), cloud fraction (CF), cloud liquid water path (CLWP), cloud optical depth (COD), cloud top pressure (CTP), and cloud top temperature (CTT) on a seasonal and annual basis, as well as during high PM_2.5concentration conditions. During the study, the average daily PM_2.5was found to be approximately 100 µg/m³ (ranging from 0.45 to 470.23 µg/m³), while the average AOD was 0.79 (ranging from 0.09 to 3.55). High PM_2.5concentrations (three to five times higher than the NAAQS annual limit) significantly influenced crucial cloud microphysical properties. The research findings aid in estimating PM_2.5using satellite-retrieved AOD and meteorological data, providing insights into aerosol and cloud properties variability during high pollution events in the heavily polluted city of Kanpur, India.