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Inference on Quantiles under Equality Restrictions
No full textThe thesis deals with the inference on quantiles of some probabilistic models under equality restrictions on parameters. In Chapter 1, we discuss the background of the problem and give a comprehensive literature on the related problems which are undertaken in the thesis. Specifically, the inference problems under equality restrictions have been discussed. In Chapter 2, we provide some basic definitions, fundamental notations and methodologies for the point estimation, interval estimation and hypothesis testing problems that help to frame the rest of the chapters. In Chapter 3, the problems of interval estimation of, and testing a hypothesis on the quantile have been considered when independent random samples are available from two and more normal populations with a common mean and possibly unknown and unequal variances. For two populations, the asymptotic confidence interval, parametric bootstrap intervals, and generalized confidence intervals have been obtained. For hypothesis testing, several tests, such as the one based on the Computational Approach Test, the likelihood ratio test, a test using an estimator of quantile, and tests based on a generalized pvalue approach, have been proposed. For several populations, in addition to the intervals proposed for two populations, we have proposed three new methods for confidence intervals, such as the two highest posterior density intervals and a confidence interval using the method of variance estimate recovery. In the case of hypothesis testing, we have also proposed three new test procedures such as the standardized likelihood ratio test, the modified likelihood ratio test and the parametric bootstrap likelihood ratio test. Chapter 4 discusses interval estimation and hypothesis testing of the quantile when samples are available from several normal populations with a common standard deviation and unequal means. The asymptotic confidence interval, an interval using the method of variance estimate recovery, bootstrap-p, bootstrap-t, highest posterior density intervals and generalized confidence interval for the quantile have been derived. We discuss several test methods for hypothesis testing, such as the one based on the computational approach test, the asymptotic likelihood ratio test, the parametric bootstrap likelihood ratio test, and tests based on the generalized pvalue approach. In Chapter 5, we obtain the confidence intervals and construct test procedures for the quantiles when the observations are from a bivariate normal population with a common mean. We derive several confidence intervals, such as the asymptotic confidence interval, a classical confidence interval using the method of variance estimate recovery, bootstrap-p, bootstrap-t and the highest posterior density. Furthermore, two generalized confidence intervals are obtained using some of the estimators of the common mean. In the case of hypothesis testing, several tests, such as the likelihood ratio test, tests based on the computational approach, and tests based on the generalized variable method, are derived. Chapter 6 deals with the problems of interval estimation and hypothesis testing of the quantile for several exponential populations with a common location and possibly different scale parameters. Several interval estimators for the quantile, such as the confidence intervals based on the generalized variable approach, parametric bootstrap approach and Bayesian intervals using the Markov chain Monte Carlo method, have been proposed. Several test procedures have been proposed, such as tests using the generalized variable approach, tests based on the parametric bootstrap method, and tests using a computational approach. In Chapter 7, we consider the problems of point estimation, interval estimation and hypothesis testing for the quantile of k( 2) exponential populations with a common location and different scale parameters under a progressive type-II censoring scheme. In the case of point estimation, we derive the maximum likelihood estimator (MLE), a modification to it and the uniformly minimum variance unbiased estimator (UMVUE) of the quantile. An estimator dominating the UMVUE is derived. Further, a class of affine equivariant estimators is derived, and an inadmissibility result is proved. Consequently, improved estimators dominating the UMVUE are derived. In the case of interval estimation, several confidence intervals, such as generalized confidence interval, bootstrap confidence interval, and the highest posterior density confidence interval, are obtained for the quantile. In the case of hypothesis testing, we propose generalized variable tests, a parametric bootstrap likelihood ratio test and the computational approach test. In Chapter 8, we consider the problem of comparing the quantiles for several (k 2) logistic populations. The conventional likelihood ratio test is applied, and the cut-off point is determined based on its asymptotic property. Further, we propose two modifications of the likelihood ratio test- a standardized likelihood ratio test and a parametric bootstrap likelihood ratio test. Furthermore, we suggest a computational approach test to test the equality of quantiles by leveraging technology. In all the cases, numerical comparisons of all the proposed methods are considered. The confidence intervals have been compared through average length, coverage probability, and a new measure called - the probability coverage density (wherever applicable). Also, all the proposed tests’ sizes (powers) have been computed using the Monte Carlo simulation procedure. The point estimators are compared using risk function. Real-life examples are discussed for application purposes
Stability, Observability and Control Analysis of DC-DC Converters Using Lie Algebra and Linear Algebra
No full textThis thesis focusses on analysis of control and stability aspects of different topologies of DC-DC converters, such as buck converter, buck-boost converter, boost converter and flyback converter. Stability analysis of DC-DC converters is necessary to design efficient controller which can have a wide range of operating region. It is crucial to check the controllability of all the system states for effective design and control of DC-DC converters because in many industrial applications the control input of dynamical systems is found to influence only a part of the system states. The thesis work includes comparison of frequency response analysis of buck converter linearized by exact feedback linearization (EFL) and state space averaging (SSA) methods, stability analysis of buck converter using Lie Algebra, controllability analysis of flyback converter using controllability transition method, local accessibility and small time local controllability analysis of buck, boost and buck-boost converters, study of nonlinear observability rank condition (NORC) based on Lie Algebra of buck and boost converters considering both equilibrium and non-equilibrium states. It is observed from the analysis of the buck converter model linearized using EFL and SSA methods operating in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) that the phase margin of the EFL linearized model is same as that of the nonlinear model for different values of duty cycle and output resistance. On the other hand, these frequency response parameters obtained from SSA linearized model do not match with that of the nonlinear model. Lie algebraic stability analysis indicates that a nonideal buck converter is stable when the MOSFET on-state resistance and diode forward resistance are equal. The converter is found to be unstable when such resistances are unequal. On the contrary, root locus plots reveal that the buck converter is stable even when these resistances are not equal. Thus, Lie algebraic stability analysis is identified to be more conservative method for stability analysis of non-ideal buck converter and importantly, such analysis is viable for applications where asymptotic stability should be assured. It is found from small time local controllability (STLC) analysis using Sussman’s theorem that the variation in duty cycle and input voltage does not affect the controllability of DC-DC converters (buck, boost and buck-boost). The findings of Lie-algebraic analysis also show that the variation in load resistance does not influence the controllability status of the systems considered. The controllability transition based analysis of DC-DC flyback converter reveals that such converter is controllable for load resistances below a critical value for a specific input voltage. Thus, a concept regarding the range of load resistances necessary to preserve system controllability is obtained and such load resistances can be considered for designing controllers. The decrease in reciprocal condition number of switching controllability gramian below controllability transition () value indicates loss of controllability, even though the system is proved to be controllable by linear subspaces method. Thus, ill-conditioned switching controllability gramian of a switched linear system specifies uncontrollability. This finding assures that controllability transition method can distinguish between the controllable and uncontrollable status of the system. NORC based observability assessment is more accurate than Kalman rank criterion of observability (KRCO) method as it considers both equilibrium and non-equilibrium states of nonlinear system. It is observed from this study that buck converter is observable for non equilibrium states and unobservable for equilibrium states. Also, boost converter in non equilibrium states is observable for specific range of duty cycle (~from 0.2 to 0.9) and becomes unobservable for duty cycle equal to 1.0. The boost converter is found to be unobservable in equilibrium states. The compendium of the study presented in the thesis will be beneficial for estimation and improvement of the performance of DC-DC converters
Transition Metal-Promoted Synthesis of Remotely Functionalized 2-Aryl Benzoxazoles from 2-Amidophenol through C-H Functionalization
No full text2- Substituted benzoxazoles are an important class of heterocycles found in several biologically relevant compounds, natural products, and designed pharmaceutical molecules. They also serve as valuable functional compounds in many organic syntheses and show a remarkable chromophoric effect. In addition to the classical methods, innovative transitionmetal-catalyzed methods have been developed to synthesize variously functionalized benzoxazoles with the aid of diverse directing groups through oxidative sp2 C-H bond activation. The ligating ability of the nitrogen atom in the benzoxazole ring has been exploited significantly for the ortho- C-H bond activation. In contrast, synthesizing the benzoxazole framework with C-H functionalization at the fused-benzene ring is less literature precedent. As such, synthesizing functionalized benzoxazole at the fused benzene ring site is challenging. The current thesis entitled “Transition Metal-Promoted Synthesis of Remotely Functionalized 2-Aryl Benzoxazoles from 2-Amidophenol through C-H Functionalization” mainly addresses our initiatives to access C4-H, C5-H and C7-H functionalized 2-aryl benzoxazoles directly with the aid of transition-metal catalyst under ligand-free conditions. The present thesis has been divided into five chapters. Chapter 1. A Short Review on Transition Metal-catalyzed Synthesis of Functionalized 2- Aryl Benzoxazoles This chapter describes the transition metal-catalyzed different methods for synthesizing functionalized 2-aryl benzoxazoles via C-H activation. In addition, a critical overview and objective of the present work were also presented. Chapter 2. Synthesis of 4-Alkenyl Benzoxazoles via Pd-catalyzed ortho C-H Functionalization of 2-Amidophenols In this chapter, one-pot direct synthesis of remotely C-H alkenylated 2-aryl benzoxazoles from the reaction of amidophenol and electronically deficient olefin in the presence of Pd-catalyst was reported. Control experiments confirm that the Pd-catalyzed anilide-directed regioselective C−H activation/alkenylation occurs at the first step by leading to ortho-alkenylated amidophenol, which subsequently underwent tandem intramolecular annulation to afford C4-alkenylated 2-aryl benzoxazole derivatives. xi Chapter 3. Access to C4-Arylated Benzoxazoles from 2-Amidophenol through C-H Activation In this chapter, a Pd-catalyzed aerobic approach to access C4-aryl benzoxazoles from the tandem C-H ortho-arylation and acid-mediated annulation of 2-amidophenol has been presented. The competing directing potential of the –NHCOR group over the –OH group was exploited for selective arylation adjacent to the amide group. One-pot hydrolysis of the resulting C4-arylated benzoxazole was also accomplished to access structurally challenging 3- aryl aminophenols for further applications. Chapter 4. Iron(III) Chloride Mediated Para-Selective C-H Functionalization: Access to C5-Chloro and C5, C7 Dichloro/Dianisyl Substituted 2-Aryl Benzoxazoles This chapter reveals the iron(III) chloride-mediated para-selective C-H chlorination and subsequent annulation of 2- amidophenol to synthesize C5- and C5, C7-chlorinated benzoxazoles. Further, the oxidative cross-dehydrogenative coupling of amidophenol with anisole by ferric chloride was presented to achieve the remotely anisylated benzoxazoles. Chapter 5. Conclusion and Future Scope In the last chapter, the present work's overall summary and future scopes have been described
Power System Reliability Assessment and Enhancement for Different Contingency Conditions
No full textA power grid in a nation or continent integrates utilities by generating stations and loads in order to meet power requirements. When such colossal power systems are involved in power transfer, the voltage stability issue typically crops up. Voltage collapse may lead to blackouts. A blackout in a power system may affect one nation politically, socially, and economically. Blackouts can only be reduced by focusing on a detailed study of the steady state and dynamic operation of the power system. A possible solution may be to increase the power system infrastructure in order to endure these blackouts. Knowledge of the most vulnerable portion of the system, such as a line or bus, is essential for this endurance. Therefore, we need to distinguish the weak and less reliable buses or lines as soon as possible in the power system operation in order to take the necessary actions for smooth operation or to maintain steady-state equilibrium. The weak bus and lines may suffer outages, leading to cascading outages. As part of the analysis in this study, the ranking of contingencies was carried out using two evaluation approaches. The two approaches, namely the “Fast Voltage Stability Index” (FVSI) and a new “Reduced Fast Voltage Stability Index” (RFVSI) or the classical approach and the soft computing approach based on Fuzzy Logic (FL), have been used for different bus systems. The RFVSI is a reduced and faster version of FVSI. The outcomes of the two approaches were compared. It is found that the Fuzzy Logic (FL) approach computes the contingency ranking in less time compared to the classical approaches. In contrast, the classical approach based on the RFVSI method calculates contingencies more correctly, producing reliable results.
Two evolving contingency screening methods are described for faster system screening of important double-line contingencies. These methods analyze the complete double-line contingencies without considering all possible double-line outages, instead of taking only a few outages for the complete analysis, which reduces computational effort and time by using predefined power system sensitivity factors. The method described in this work is used in an Indian 62 Bus power system, and promising results are obtained. The work calculates the “Total Transfer Capability” (TTC) and the “Available Transfer Capability” (ATC) in different contingency conditions, such as line outages and generator outages. The most common continuous power flow method is utilized for TTC calculations. These calculations are useful for power wheeling in different power systems for power trading purposes in deregulated power systems.
Most of the power systems operate at their highest loading limits these days. Therefore, a small disturbance might bring the system to instability or oscillatory mode. In order to operate the system in a steady state, the system should be returned to the steady state in the event of a fault or any other disturbance. The Contingency in the power system is a severe problem, which may make the system insecure. There are several methods to mitigate the contingencies. However, it is most important to choose the point of action faster so that necessary action can be taken. The line outage contingencies, and the contingencies due to the outage of generators, affect the small signal stability of the system. The influence of generator outages on other generators has been investigated in this study using small-signal analysis. It is necessary to study the impact on the other generators present in the system so that essential control actions can be taken to reduce the generators' cascading outage. The damping of the low-frequency oscillations created due to the outages by different control actions, such as the application of “Power System Stabilizers” (PSSs), is described in detail.
In the event of contingencies such as generator outage or line outage conditions in a power system, the transmission lines in the network may be overloaded, leading the system to approach cascading outages. In generator outage conditions, the other generators in the system may fail to supply the load, which causes stability issues such as loss of synchronism in the system. The voltages of the buses of the system also decrease. In order to overcome these issues, a possible solution is to integrate renewable energy sources (RES) at the network's appropriate location for injecting active and reactive power into the network. With the RES in the proper places, the power transfer capability of the network could be improved along with the minimization of the line losses and the improvement of the voltage profiles of the buses. The optimization method involves the minimization of the "Reduced fast voltage stability index" and the minimization of "Transmission line losses".
All the methodologies are applied to the IEEE-14, IEEE-30, and practical Indian 62 Bus power systems
Molecular Dynamics Simulation of Deformation Behavior of Nanocrystalline Al and CNT Reinforced Nanocrystalline Al Nanocomposites
No full textA new class of nanocomposites called metal matrix nanocomposites with modest amounts of nanoparticles with large specific surfaces as reinforcement exhibit exceptional physical and mechanical characteristics and have potential uses in various fields. These reinforcements interact more intensely with the metal matrix, improving the nanocomposites' mechanical, thermal, structural, and physical properties. Metal matrix composites reinforced with carbonaceous nanofillers such as carbon nanotubes (CNT) display exceptional performance even in harsh environmental circumstances. Material scientists have always been fascinated by the lack of structural flaws in carbon nanotubes, which have unmatched mechanical capabilities, for their possible inclusion in a metal matrix to produce exceptional mechanical stability. The primary contribution of this thesis is to provide a detailed knowledge of the mechanical performance and deformation behaviour of nanocrystalline (NC) materials and CNT reinforced NC Al NCs subjected to random, uniform, and columnar grains under various loading situations and operating parameters at atomic level using molecular dynamics simulation. It is challenging to conduct experimental research on the underlying deformation mechanisms for NC materials and CNT reinforced NC nanocomposites since it is costly and time-consuming. MD simulation is a trustworthy and efficient method to pinpoint the underlying deformation mechanism at the nanoscale. The present study starts with assessing the mechanical performance of NC Al and CNT reinforced NC Al nanocomposites subjected to random grains in metal matrix material at two strain rates, three armchair chirality’s, and three operative temperatures (10 K, 300 K, 681 K) using MD simulations. The grain size effect on the considered specimens has been analysed with respect to the volume fraction of CNT and temperature variation. In addition, the underlying deformation mechanism has also been investigated for NC Al and CNT-NC Al nanocomposites. The hybrid potentials (EAM, AIREBO, and LJ) have been considered to carry out the tensile deformation on considered nanocomposite specimens. The structural variations and defect evolution have been investigated during the deformation. An enhancement in both strength and ductility is observed in the CNT embedded NC Al specimens with respect to NC Al specimens. Such improvement is significant in case of (30,30) CNT embedded NC Al specimens. Further, emphasis was given to studying the underlying deformation mechanism of random grains in predetermined parallel and perpendicular cracks in NC Al and CNTs reinforced NC Al nanocomposites under uniaxial tensile loading using molecular dynamics simulations with a mechanical performance at three different operative temperatures and three armchair chiralities. The stacking faults interaction with various dislocations, twin boundary, CNT-matrix interface, and grain boundary widening has been elucidated in detail with atomic snapshots during the tensile deformation of NC Al and CNT-NC Al nanocomposites. The next objective is to investigate the creep-ratcheting behavior of NC Al and CNT-NC Al nanocomposite specimens using molecular dynamics simulations at three armchair chiralities and temperatures. The influence of deformation temperature on creep-ratcheting behavior has been studied and associated with underlying mechanisms based on the structural evolution of the material identified. The vacancy concentrations and dislocation densities have been evaluated at the end of each stage of the creep-ratcheting process for two ratcheting stress ratios, three different temperatures, and chiralities. The predominant stages involved in the creep-ratcheting deformation process are cyclic hardening and cyclic softening. Conversely, the primary, steady, and tertiary regions are observed from the creep-ratcheting plots. Finally, it is seen from the dislocation analysis that the Shockley partial and full dislocations are the driving dislocations for the creep-ratcheting deformation process. Then this work is extended to study the creep-ratcheting behavior of columnar NC Al at different temperatures. The cyclic hardening and cyclic softening phenomena are examined during the creep-ratcheting process. The grain boundary-based deformation mechanisms of columnar NC Al are elucidated in detail. The effect of dislocation density and types have been studied along with structural analysis. Finally, the deformation behavior of NC Al and CNT reinforced NC Al nanocomposite specimens (CNT-NC Al NCs) have been inspected under torsional loading. The evolution of CNT-NC Al NCs at the nanoscale, the changes in crystal structure at the atomic scale, and their correlation with defects are investigated at different stages of torsional deformation. The fracture path for NC Al and CNT-NC Al NCs is seen along the grain boundary, and the CNT fracture process in torsion is also studied. In summary, the work presented in this thesis offers a fundamental understanding of the mechanical performance and deformation mechanism of different grains (random, uniform, and columnar) of NC Al and CNT-NC Al nanocomposites during the tensile, creep-ratcheting, and torsional processes. Additionally, this cutting-edge simulation method helps to comprehend the impact of temperature, volume fraction, and operating parameters on the behaviour of nanofiller based nanocomposites subjected to mechanical properties, structural analysis, and defect evolution
Molecular Design and Synthesis of d- (V and Ni) and p- (Sn) block Metal Complexes with Dibasic Ligands: Biological, and Catalytic Relevance
No full textThe magnificent roles of cisplatin as a DNA-reactive therapeutic and gadolinium complexes as MRI diagnostics enthused the progress of metal-based therapeutics or diagnostic agents in the modern era. In such inorganic pharmaceuticals or probes, coordination chemistry in the biological environment or at the target site reclines at the heart of their modes of action. Therefore, molecular designing of new metal-based drugs or imaging probes by tuning the coordination environments, provides the opening in the alteration and improvement of such agents, thus raising metal-based compounds as promising pharmacological candidates. Keeping the importance of metal complexes in the biological aspect, this dissertation deliberately outlines the molecular design, synthetic methodology, characterization, and thorough investigation of the chemical properties of the transition metals (V, and Ni) and main group metal (Sn) complexes containing a variety of ONNO, and ONO donating salan, unsymmetrical-salen, aroylhydrazone, and Schiff base ligands with preference to their pharmacological activity. Characterization of all the new compounds has been done through numerous physicochemical (elemental analysis), spectroscopic (UV-vis, IR, and NMR), and spectrometric (ESI‒MS/ HR-ESI-MS) techniques. Solid-state structures of the complexes have been determined through single-crystal X-ray diffraction analysis. The photophysical characterization of some of the complexes has also been examined through UV-vis and fluorescence spectroscopy. The solution behavior of complexes in aqueous or biological media has been checked before studying them for any biological assay, in order to comprehend their transformation, interconversion, variations in coordination geometry, and change in nuclearity taking place, if there is any, in the solution phase. This will ultimately help to find out the actual species responsible for the overall observed biological activities. Furthermore, a detailed biological study of these complexes has been done by evaluating their interaction with biomolecules such as CT-DNA and proteins (HSA and BSA) by using various spectroscopic techniques like UV-vis, fluorescence, and circular dichroism. Also, the in vitro cytotoxicity potential of the synthesized complexes has been assessed against various cancer [human lung carcinoma (A549), human cervical cancer (HeLa), human breast adenocarcinoma, (MCF-7), and human colorectal adenocarcinoma (HT-29)], and noncancerous cell lines [mouse embryonic fibroblast cell line (NIH-3T3)]. In addition, for highly toxic compounds, the mechanism of cell death has been evaluated by following various traditional procedures well-established in the literature i.e., DAPI nuclear staining, AO/EB staining, cell cycle analysis, Annexin V/PI double staining apoptotic assay, cellular uptake analysis through confocal and flow cytometer, ROS generation, etc. On the other hand, fluorescent active and low-toxic compounds have been studied for bioimaging applications. For this application, their photostability has been checked and live cell confocal images have been taken to find out their specific localization in cellular organelles. From the overall studies, the test compounds are found to be a good binder with DNA and proteins. Also, based on the ligand environments, the role of the chosen metal, cellular uptake capacity, lipophilicity, and cytotoxicity, the synthesized complexes are defined as better cytotoxic agents for killing cancer cells or bioimaging probes for effectively tracking cellular organelles. The obtained results herein showed parallel, or in some cases even better in vitro cytotoxicity in contrast to many clinically testified chemotherapeutic drugs and some of the complexes might be used as an equal or better organelle tracking agent as compared to commercially available organelle trackers. Apart from this, considering the high catalytic importance of Ni and salen ligands, here some Ni(II)-unsymmetricalsalen complexes have been studied as catalysts for the synthesis of 2-amino-3-cyano-4H-pyrans derivatives through multicomponent reactions
Phase Formation, Microstructure, and Magnetocapacitance Behaviour Of Ex-situ Combustion Derived Magnetodielectric Composites
No full textMagnetodielectric (MD) compounds belong to multifunctional materials which can show both magnetic and dielectric along with MD properties including magnetocapacitance (MC) and magnetoresistance (MR). MD properties depend on the interface of both dielectric and magnetic phases of the composite. In this work, a novel combustion derived ex-s tu synthesis was adopted to develop MD composites. Here, one of the phases in the calcined powder form was dispersed in precursor of other phase followed by combustion. In this approach, by interchanging the dispersed (varying particle size) and precursor can alter the microstructure during sintering, and it can tune MD properties of the composites. Based on this concept, the prime objective of this research work is to develop ferrite- BT and BT-ferrite composites via ex-situ combustion in which the gel-combustion/solid-state derived calcined powders of dispersed phase (i.e., 30 wt % ferrite / 70 wt % BT in ferrite-BT / BT-ferrite composite, respectively) were introduced into the precursor to tune the microstructure (in terms of the distribution of BT, CF and in-situ phases) and explore the dielectric, magnetic and frequency/field dependent MC and MR of these composites. The calcined (800 °C and 1200 °C) powders of (GCF/SCF)800/1200 (i.e., gel-combustion/solid-state derived CF) and (GBT SBT)800/1200 (i.e., gel-combustion/solid-state derived BT) have been used as a dispersed phase to develop ferrite-BT and BT-ferrite composites, respectively. These composite powders were calcined at 800 °C/4h, pelletized and sintered at 1000 °C, 1100 °C, 1200 °C and 1250 °C. Different characterization techniques including XRD, FESEM, Raman, dielectric, magnetic, and MD have been performed on all composites. The results are analysed and compared among each other considering the source and size of the dispersed phase, as well as sintering temperature of the composite. The percentage of BT and HBT found inversely proportional to each other, and a similar relation was observed between CF and BHF phases. Moreover, the presence of in-situ phases (BHF and HBT) was higher in GCF/SCF/GBT/SBT-800-based composites. Highest HBT and BHF phases were observed in ferrite-BT composites. The spherical or polyhedral BT/CF and plate-like HBT/BHF phases were found indistinguishable and evenly distributed in the GCF/SCF/GBT/SBT-800-based composites sintered at lower temperatures. Higher permittivity was observed at lower frequencies due to the space-charge polarization caused by electrical inhomogeneity in the composites. The permittivity of both ferrite-BT and BT-ferrite composites was found dependent on the type of dispersed phase and sintering temperature. The permittivity at 1 MHz in all the composites (except [SCF800]→[ferrite-BT]-1250) was found directly proportional to the relative density and the percentage of the dielectric phase. The magnetization of all the composites was partially saturated due to the presence of non-magnetic BT and/or plate-like HBT phases. The MC% response of the composites was found mostly field-dependent and analogous to the MR% response, indicating the influence of space-charge polarization (M-W polarization). The highest positive magnetocapacitance percentage of ~ 45% was observed in the [GCF1200]→[ferrite-BT]-1200 composite, which contains higher plate-like HBT phase. Furthermore, the magnetocapacitance behaviour of the composites was correlated with the dM/dH behaviour, field and frequency-dependent magnetoresistance, and Cole-Cole plots. The results of all composites are analysed with respect to the type/interchanging dispersed phase, in-situ phases, microstructure, sintering temperature, density, resistivity, MC and MR and also compared with the relevant literature. The developed MD composite may have a potential application in the field of magnetoresistive sensors, actuators, transducers, spintronic devices, and memory devices
Design of Chipless RFID Transponders for Retail and Healthcare Applications
No full textChipless radio frequency identification (RFID) is a low-power, non-line-of-sight wireless technique that has the potential to regulate the automatic identification (Auto-ID) industry with its various applications in healthcare, automated identification, object tracking, security, and authentication with less human intervention. Chipless RFID is fundamentally an alternative solution to conventional high-frequency (HF) or ultrahigh-frequency (UHF) RFID. Numerous industries, including fare collection, item monitoring, road tolls, and medical applications, heavily rely on RFID technologies. Businesses are becoming increasingly interested in such a new and promising technology because of characteristics like orientation independence, large storage, low cost, a large detection range, robustness to ambient conditions, and the non-intervention of human labour. This dissertation aims to investigate whether chipless planar microstrip resonators can be successfully applied to the physical layer of a chipless RFID system. To reduce the cost of a passive tag, we must not only increase the coding capacity of resonator-based tags but also limit their overall dimension using an inexpensive substrate by ensuring that the control structures won't harm the system's performance. The major goal is to investigate various resonator types and how they might be used to compact passive RFID transponders for use in retail and healthcare utilities using inexpensive substrates like FR4. In this research work, a range of resonators, from 1-bit to 15-bit transponders, are analyzed using rectangular, modified rectangular, square, octagonal, split-ring, complementary, and hybrid resonators. This study suggests innovative design choices to miniaturize passive transponders that combine a hybrid design with stepped impedance resonators (SIR) and rectangular stub resonators. By removing constraints including cost, size, and coding capacity, the analysis seeks to help the development of chipless RFID technology progress. With a physical footprint of 32 mm × 15 mm and a maximum radar cross-section (RCS) response of -25.66 dBsm, the design is guaranteed to have a 10-bit coding capacity. The RCS response has been examined at the receiver using a rectangular windowing approach, which improves the RFID system's coding capabilities and security characteristics. Additionally, Hamming, Hanning, and Bartlett windows are used and evaluated to demonstrate the efficacy of windowing approaches in RFID coding. To increase detection accuracy, the performance of the tag is examined at various tilt-angles and read distances. A reference wideband horn antenna is used as the interrogator to study the tag detection procedure, having gains of 6.6 dBi and 18.77 dBi at 0.5 GHz and 5.8 GHz, respectively. The measurements are carried out in a bistatic mode, and the outcomes employing frequency domain analysis with a maximum radar cross-section of -15 dBsm justify the 15-bit coding capacity of the chipless tag. A multi-narrow band chipless RFID reader antenna based on a modified rectangular resonator is also analyzed. The reader antenna is fabricated and measured to validate multiple narrowband behaviours. The measurement results show that the reader antenna can detect 11-bit multi-frequency coded chipless tags and depict gains of 4.7 dBi and 5.2 dBi at 0.58 GHz and 2.4 GHz, respectively. The cubic interpolation approach as a signal processing technique is applied at the reader end to eliminate the unnecessary drops at the measurement. Further study of the fundamental limit demonstrates that the physical dimensions of the proposed antenna and the radiation characteristics fulfil the dimension’s criteria. The multiple narrow-band responses of the reader antenna can be suitable to detect multi-bit tags, which are of high demand because a multi-bit transponder can be used for multiple frequency applications for hassle-free wireless environments, viz. tracking, retailing, identification, and healthcare utilities
Urbanization and its Impact on Hydrologic and Environmental Parameters of Urban Indian Catchments
No full textThe principal factor responsible for the hydrologic and climatic alterations in a tropical country like India is associated with every increasing proportionate area under impervious surface. Determination of imperviousness, which is defined by total impervious area (TIA) and effective impervious area (EIA), is mandatory for hydrological modelling of water quantity and quality in urban areas. In this study, a multilayer deep learning model Convolutional Neural it automatically detects the spatial features from image input and is gaining attention for their capability of achieving better classification accuracy. With estimation of TIA, its impact on different environmental parameters (Land surface temperature, Pollution (air/water/solid waste) parameters and Diurnal temperature range (DTR)) and hydrological parameters (groundwater recharge, rainfall extreme indices and surface runoff) were also studied. A more realistic automated method is suggested in this study to determine EIA by integrating the remote sensing data, the digital format of the drainage network, and a digital elevation model (DEM) of the study areas. A graphical user interface (GUI) called EIA estimator is developed for automatic creation of EIA maps. An effort is made to derive a relationship between TIA and EIA and it is generalized based on some common parameters like TIA growth, drainage density, stream order, flow length and topographic wetness index (TWI) of study areas. Based on these different categories several power and linear relationships were obtained for easily measurable TIA and hydraulically relevant EIA in urban catchments of India. There were no such relationships available in the literature for an urban Indian catchment and it would aid planners and decision makers with quick initial estimate for surface water quantity and quality problems. This research concludes with implementation of different deep learning models (RNN, LSTM and GRU) for time series forecasting of environmental and hydrological datasets univariate time series prediction and from the error analysis it was observed that LSTM performed very well than other two model algorithms. On the other hand, a single model could not produce the most accurate results and might be vulnerable to mistakes like bias and volatility. To cut down on these inaccuracies and enhance predictions, several models were merged into a single one. This technique of training different machine learning models and integrating their outputs is known as ensemble learning. In this study, the simplest ensemble technique i.e., averaging is implemented. The final prediction is made using the average of prediction outputs from Vanilla LSTM, Stacked LSTM and Bidirectional LSTM were averaged parameters for the year 2025. These deep learning models were first implemented with DTR Network (CNN) is implemented for estimating TIA of urban Indian cities during 1995-2021 as and denoted as Ensembled LSTM (ELSTM). ELSTM was applied to other hydrological and growing urbanization as later is unescapable
Study of Spatial Distribution and Health Risk Assessment due to Arsenic Contamination in Bihar, India, for its Detection and Bioremediation
No full textThe shortage of drinking water is a matter of concern in today’s world. Arsenic (As) is a naturally occurring and highly toxic environmental impurity found in rocks, soil, and water in contact with them. Natural As concentrations above their permissible limits (>10 μg/L) is an environmental crisis all over the globe and one of the biggest in India. Arsenic toxicity and human health are intensely connected. Human health risks associated with acute As toxicity include DNA damage, mutations, neurological disorders, respiratory diseases, and cancer in the liver, kidney, and skin. India's middle Gangetic plains, which make up 89% of the state of Bihar and have potential alluvial aquifers, are severely damaged. One of the hardest impacted places by geogenic As is the Bhojpur district of Bihar, which is situated in the center of the Gangetic plains in the flood-prone Sone- Ganga interfluvial zone. The present investigation starts with a study that evaluated the amounts of geogenic As and other heavy metals influencing the release of As in the aquifers inside the drinking water sources in the Bhojpur district of Bihar, India. In six nearby villages near the River Ganga, namely Bakhorapur, Gaziapur, Parasrampur (or Kanhachhapara), Saraiya, Paiga, and Gundiinin, hand-dug wells were used to collect 18 water samples in triplicate. Arsenic, zinc, manganese, and iron contamination levels in the area were found to be extremely high according to the physicochemical parameters, ionic content, and heavy metal analyses of the water samples that were collected. Iron and As concentrations ranged from 0.17 to 1.16 mg/L and 24.3 to 168.07 μg/L, respectively, indicating high groundwater removal for irrigation and domestic use with a strong link between the two elements. The heavy use of chemical fertilizers and pesticides in the area is blamed for the elevated zinc concentration there. Manganese concentrations were also higher, ranging from 0.05 to 1.15 mg/L, mostly as a result of the industrial activities that are concentrated in metropolitan areas. The overall water quality in the region is slightly contaminated, but the risk associated with it is modest, according to an assessment of the human health risk among two population groups. The range of the water quality index, from 29 to 48, indicated poor water quality. From the previous study, it was revealed that a high concentration of As in groundwater exists, which is the sole source of drinking water for the villagers. The toxicity associated with acute As poisoning is well-known and established. Because of this toxicity, it is crucial to find and identify these As-rich aquifers in order to protect human health. As a result, individuals unknowingly eat As, a colourless, tasteless, and odourless heavy metal, through drinking water that contains it as well as through irrigational operations, which has an impact on the food chain. Therefore, there is a need for a quick, simple, and affordable As detection kit so that any regular person, at any time, can do so at a very low cost without the need for special training or laboratory conditions and protect themselves from the toxic and carcinogenic effects of this infamous heavy metal (As). Inductively coupled plasma mass spectrometers (ICPMS) and atomic absorption spectrometers (AAS) are two systems that can be used to detect As and provide both qualitative and quantitative data. These systems have shortcomings, such as larger equipment that makes them difficult to move about. Additionally, because to the high cost of the equipment, they can only be found in advanced research labs and require trained employees to run the instruments in order to carry out the intricate and time-consuming analytical procedure. To ensure that the general public can detect the presence of As in the water sample at any time and at a very reasonable cost without any special training or lab requirement, there is a need for a quick, user-friendly, and cost-effective As detection kit. This will protect them from the carcinogenicity and toxic effects of As. The goal of the current project is to create a low-cost kit for paper-based As detection. Despite the availability of As paper-based field test kits, the majority of methods for the detection of As rely on the production of arsine gas. Due to the fact that gas mobility is significantly higher than that of liquid mobility, the emission of this arsine gas is extremely harmful to human health. The currently available paper-based test kit was developed using the silver nitrate immobilization method (AgNO3). The kit was examined for factors such as colour development for various As forms (As3+ and As5+) and concentrations, test strip storage conditions, the impact of various interfering agents on colour development, and optimization of AgNO3 solution. Potassium permanganate (KMnO4) was used as the oxidant for oxidizing As3+ to As5+. A colour gradient scale was created from the colour established for various As concentrations to roughly measure the concentration of As. The kit will cost Rs. 3.92 per sample, which is 70 to 100 times less than the cost of current procedures, according to the cost study, which was conducted. Under Intellectual Property Rights India, the current method for creating the kit and the kit itself have both been applied for patent with the application number 202231027806. The presence of As in groundwater and its associated toxicity is very much harmful to human health. Therefore, the next study aimed at the removal of this As along with other heavy metals using plant-based biosorbents and microorganism-based biofilm-mediated remediation. In the plant-based approach, biosorbents prepared from novel Colocasia esculenta stem and Artocarpus heterophyllus (jackfruit) seed biomass were studied for the removal of As and other heavy metals. Biosorbents from the stems of the Colocasia esculenta plant and Artocarpus heterophyllus (jackfruit) seed biomass were able to successfully and efficiently remove As along with other heavy metals from individual and as well as from heavy metal mixture solution. The adsorption of As and other heavy metals happened via endothermic and spontaneous processes and followed the pseudo-second-order kinetics model for both biosorbent experiments, according to the findings of the thermodynamic and kinetic study. In order to analyze the equilibrium data for both biosorbent studies, eight different isotherm models were used. Zeta potential and a CHNS analyzer were used to characterize the biosorbents. Utilizing SEM-EDX, FTIR, and XRD analyses, further characterization of the biosorbents both before and after adsorption was investigated. In the microorganism-based approach, a biofilm-mediated bioremediation study of As and other heavy metals was studied. This was carried out using a multi-metal resistant, gram-positive, non-virulent bacterial strain, Bacillus sp. GH-s29 strain isolated from the As-contaminated groundwater of Bhojpur district, Bihar, India. The strain's biofilm mode was able to remove heavy metals not only from individuals but also from multi-metal solutions. These findings were further supported by the results of the strain characterization using SEM-EDX and FTIR analysis. The maximum removal of As5+, Cd2+, and Cr6+, was observed to be 73.65%, 57.37%, 61.62%, and 48.92%, 28.7%, and 35.46%, from individual metal solutions and multi-metal solutions, respectively. The effective sequestration of the positively charged metal ions from solutions is facilitated by the presence of various negatively charged functional groups on the EPS, including hydroxyl, phosphate, sulphate, and carboxyl. This hypothesis was supported by the results of the FTIR study. The final study aimed at the development of a bio-filter column to remove As from the groundwater. In the prior investigation, two plant-based strategies and a biofilm-mediated strategy for As removal were validated. Both biosorbents were mixed in equal parts and used as a result of the plant-based system's high removal efficiency and availability. In order to remove total As from the groundwater, a small-scale plant-based bio-filter column has been devised and developed in the current work while considering its possible applications in the urban, rural, and industrial sectors. After testing the effectiveness of oxidation with three different oxidants, it was discovered that chlorine, at an ideal concentration of 0.3 mg/L, had the maximum efficacy in oxidizing As (III) to As (V). The study also discovered that when the initial As concentration was 250 μg/L, the X bio-filter column was capable of filtering 96.29% of the total As over the course of 60 days at a flow rate of 1.5 L/h. According to the research, the bio-filter column was capable of filtering out As up to a concentration of 1000 μg/L, but after that, its ability to do so started to decline. With the AAS inquiry, interference analysis of several anions and cations was performed. The analysis's findings showed that PO4 3- had the greatest inhibitory effect, followed by CO3, 2- and Cl-. The possibility of PO4, 3- and CO3, 2- ions competing for the As binding sites in the biosorbent could be the reason for decline in As adsorption. However, it was established that a rise in Ca2+ and Mg2+ concentrations was closely related to a rise in As adsorption strength. This might be because the hydration reaction on the biosorbent is aided by the presence of Ca2+ and Mg2+ ions. The bio-filter column's best removal performance was noted at a capacity of 1000 L volume. This shows that the bio-filter column can remove total As from water that is polluted with As up to a maximum volume of 1000 L before its removal efficiency starts to drastically decline. Therefore, it may be stated that the developed bio-filter column can remove total As from water that is polluted with As for a maximum of 1000 L volume