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Item Heat Transfer Analysis on the Expedition of Temperature Distribution and Bubble Behavior from Nucleation to Critical Heat Flux during Pool Boiling(Indian Institute of Tehcnology, Jodhpur, 03-07-2023) Kothadia, Hardik B.The phase change heat transfer processes are widely implemented for heat extraction as they utilise both sensible and latent heat (Rohsenow and Griffith, 1955). The capability to remove the higher magnitude of heat at low wall superheats, and the lack of moving parts makes pool boiling appealing (Memmott and Manera, 2011). Pool boiling is economical, simple, and prevalent among all available cooling schemes. The utilization of the aforementioned technique is widely implemented for thermal management in nuclear industries and in microelectronic devices. Conventional air cooling systems cannot handle these devices cooling requirements which may be due to their low heat transfer performance. In such instances, pool boiling, and droplet evaporation techniques can be implemented. Nowadays, the nuclear industries, renewable energy sectors, and power plants are implementing compact heat exchangers as preheaters, regenerators, and intermediate heat exchangers (Pattanayak et al., 2022) (Pattanayak and Kothadia, 2020). These compact heat exchangers are basically of tubular or plate-type. Therefore it gives the urge to study the heat transfer characteristics of those heat exchangers and analyse the methodologies that can enhance the heat transfer from the surface of tubes and plates (Pattanayak et al., 2022). The lack of qualitative theories, quantitative data, and explanations in the area of critical heat flux (CHF) in tube and plate makes it an interesting domain of research. There is limited research explaining the effect of high, substrate and liquid temperatures, on droplet evaporation. There is a scarcity of research in analysing the heat transfer coefficient during the evaporation process (Pattanayak et al., 2021) (Pattanayak and Kothadia, 2022). The research highlights the critical heat flux (CHF) studies on mini-channels, micro-channels, and plates during pool boiling under uniform heat flux conditions. Identification of the tube and plate length and diameter beyond which CHF becomes independent of the dimensions is discussed. The effect of tube and plate orientations and pool subcooling on CHF has been analysed. Different regimes of pool boing under uniform heat flux conditions are discussed based on bubble behavior. The instantaneous heat transfer coefficient during droplet evaporation is analysed. The CHF data are used to derive an empirical correlation that includes the impact of subcooling, orientation, and dimensions (Pattanayak et al., 2023). In the case of the analysis of compact heat exchangers, SS 304 tubes and plates are used. The orientation is changed from 0ᵒ to 90ᵒ for tubes and 0ᵒ to 180ᵒ for plates. The length and diameter of tube is varied from 50 mm to 1000 mm and 1.2 mm to 9 mm, respectively. The water pool is kept at 30°C, 50°C, 75°C, and saturation temperature. The length of the plate is varied from 50 mm to 300 mm. The width of the plate ranges from 10 mm to 20 mm. The pool is maintained at 25℃ and saturation temperature corresponding to ambient pressure. It has been noted that the severity of CHF lessens as pool temperature rises. For a particular pool temperature, the shortest length has a higher magnitude of CHF. As tube diameter and width expand, CHF values decrease. In the case of tubes, the CHF value is larger for horizontal orientation than vertical orientation.In the case of the analysis of compact heat exchangers, SS 304 tubes and plates are used. The orientation is changed from 0ᵒ to 90ᵒ for tubes and 0ᵒ to 180ᵒ for plates. The length and diameter of tube is varied from 50 mm to 1000 mm and 1.2 mm to 9 mm, respectively. The water pool is kept at 30°C, 50°C, 75°C, and saturation temperature. The length of the plate is varied from 50 mm to 300 mm. The width of the plate ranges from 10 mm to 20 mm. The pool is maintained at 25℃ and saturation temperature corresponding to ambient pressure. It has been noted that the severity of CHF lessens as pool temperature rises. For a particular pool temperature, the shortest length has a higher magnitude of CHF. As tube diameter and width expand, CHF values decrease. In the case of tubes, the CHF value is larger for horizontal orientation than vertical orientation.In the case of the analysis of compact heat exchangers, SS 304 tubes and plates are used. The orientation is changed from 0ᵒ to 90ᵒ for tubes and 0ᵒ to 180ᵒ for plates. The length and diameter of tube is varied from 50 mm to 1000 mm and 1.2 mm to 9 mm, respectively. The water pool is kept at 30°C, 50°C, 75°C, and saturation temperature. The length of the plate is varied from 50 mm to 300 mm. The width of the plate ranges from 10 mm to 20 mm. The pool is maintained at 25℃ and saturation temperature corresponding to ambient pressure. It has been noted that the severity of CHF lessens as pool temperature rises. For a particular pool temperature, the shortest length has a higher magnitude of CHF. As tube diameter and width expand, CHF values decrease. In the case of tubes, the CHF value is larger for horizontal orientation than vertical orientation.The study demonstrates that for horizontally oriented tubes, CHF fluctuation is negligible beyond a length of 500mm, regardless of diameter. According to the study performed for vertical channels, CHF fluctuation is negligible for tubes with a diameter more than 2.5 mm beyond a length of 200 mm. The vertical orientation of the plates results in a higher CHF magnitude as compared to the horizontal upward and downward orientations respectively (Pattanayak and Kothadia, 2020), (Pattanayak et al., 2021), (Pattanayak et al., 2023). The hydrophobic surface of copper electrodeposited tubes exhibits a lesser CHF magnitude than the uncoated surface and is efficient for phase change heat transfer applications in lower heat flux regimes. Furthermore, the analysis of heat transfer during droplet evaporation is conducted to study the effect of surface and liquid temperature on the instantaneous heat transfer coefficient. It is observed that the evaporation rate is higher for copper than aluminum. The instantaneous heat transfer coefficient increases with the temperature of droplet evaporating on a given substrate and is higher for copper. When substrate temperature increases for a given droplet temperature, the instantaneous heat transfer coefficient increases (Pattanayak and Kothadia, 2021) (Pattanayak et al., 2022). The regimes from natural convection to CHF limit in a subcooled pool of water maintained under uniform heat flux conditions are studied for SS 304 upward-facing plates of different dimensions (Clifton and Chapman, 1969) (Pattanayak et al., 2022). During the heat transfer process, the temperature distribution along the plate is examined. The Nusselt number is seen to be independent of aspect ratio (Pattanayak et al., 2022) (Pattanayak and Kothadia, 2022). The Nusselt number rises when the plate length and width are independently increased. The study is also carried out in saline water of solutions with varying salinity from 0%, 0.2%, 0.5%, and 2%, and is observed that beyond salinity 0.2%, the heat transfer coefficient decreases (Pattanayak et al., 2022).Item Dynamics of the Homographic Ricker-like maps(Indian Institute of Tehcnology, Jodhpur, 29-02-2024) Chandramouli, V.V.M.S.In nature, the number of individuals of a species or a community of species varies over time within a region or territory. To address challenges in studying living systems due to these variations, mathematical modeling plays a crucial role in the development of an integrative point of view. Mathematical modeling of the population deals with the growth of the species and intrinsic interactions between each organism and its environment. The population modeling was pioneered by Verhulst in the 19th century with the introduction of the Logistic model. Among the several single-species models, one of the crucial population models is the Ricker population model, which was proposed to mathematically represent the stock and fisheries. The Ricker map and its various modified forms have been reviewed by several researchers [Ricker, 1954; Elaydi and Sacker, 2010; Liz, 2018; Rocha and Taha, 2020]. When the growth function of the Ricker map is defined by the Holling type II functional response, then the resulting map is a Homographic Ricker map. The nonlinear dynamics and bifurcation structure of the Homographic map have been discussed by L. Rocha in [Rocha et al., 2020]. The aim of the thesis is primarily to investigate the diverse dynamical properties of the q-deformed Ricker map, the q-deformed Homographic map, the 2D Homographic Ricker map, and the delayed 2D Homographic Ricker map. This study mainly focuses on the various dynamical aspects of these models, which involves the analysis of their nonlinear dynamics, singularities, intersections of different fold and flip bifurcation curves using bifurcation theory, and the exploration of the transition from periodic to chaotic attractors. In the first part of the thesis, we apply a deformation scheme [Jaganathan and Sinha, 2005; Tsallis, 1988] to the classical Ricker map and obtain a q deformed Ricker map, namely the q-Ricker map. We show that the q-Ricker map proclaims many exciting phenomena that are remarkable in one-dimensional dynamical systems, such as the presence of coexisting attractors, physically non-observable chaos, hydra paradox, bubbling effect, and extinction. We prove that the intersection of the fold and flip bifurcation of the curve gives a singular point of codimension greater than two, and that singular point merges with its associated cusp point. Finally, we show that a certain amount of deformation in the system can keep it in equilibrium; however, excessive deformation causes extinction [Aishwaraya et al., 2022]. Next, we discuss the analytical study of the q-deformed Homographic map (q-Homographic map).The notions of false derivative and the generalized Lambert W function of the rational type are useful in estimating the upper bound on the number of fixed points of q-Homographic map. Further, we explore the process of chaotification of the q-deformed map to enhance its complexity which involves incorporating the residue obtained from multiple scaling of the map’s value for the subsequent generation through the utilization of the multiple remainder operator [Moysis et al., 2023]. After the chaotification, the q-Homographic map shows high complexity and the presence of robust chaos, which has been theoretically and graphically analyzed using various dynamical techniques. In addition, we use the feedback control technique [Din, 2017] to control the period-doubling bifurcation and chaos in the q-Homographic map. In the second part of the thesis, we apply the Holling type - II functional response as a growth function in the classical two-dimensional Ricker map and propose a discrete-time competition model, namely the two-dimensional (2D) Homographic Ricker map. We discuss the boundedness of the solutions and the uniqueness of the coexisting fixed point of the proposed map. With the help of critical curves and singular points, we explain the geometry of the map and prove that all the points in the domain of the 2D Homographic Ricker map are either regular, fold, or cusp in nature. Furthermore, we use the centre manifold theory to explain the local stability of the fixed points of the proposed map. Using bifurcation theory, we derive some conditions under which the map exhibits the flip bifurcation [Aishwaraya and Chandramouli, 2023]. We further introduce a delayed 2D Homographic Ricker map by incorporating the delay terms in survival functions and small leak terms in the competing populations. We analyze the persistence, boundedness, invariance, and asymptotic behavior of the proposed map. Additionally, numerical simulations are employed to elucidate the stability and bifurcation analysis of the competing population. In the final part of the thesis, we study the combinatorial tools, namely the Hofbauer tower and the kneading map for a class of symmetric bimodal maps. We discuss the construction, various properties, and geometrical interpretation of these tools. Further, with the help of the Hofbauer tower, we define the cutting times associated with the bimodal map and propose an algorithm to compute the cutting times. Finally, we describe the splitting and co-splitting of the kneading invariants using the cutting and co-cutting times, respectively.Item Physical Layer Security and Performance Evaluation of Power Line Communication Systems(Indian Institute of Tehcnology, Jodhpur, 01-10-2024) Mathur, AashishPower line communication (PLC) is an information and communication technology (ICT) that enables two-way digital communication over existing electric wires or power distribution networks [1]. In recent years, PLC has been the subject of significant interest from researchers, industry, regulatory authorities, and standardization organizations owing to its inherent advantages and applications [2]. Specifically, PLC offers universal network coverage due to the omnipresence of wired infrastructure from urban to rural or remote areas. As a result, PLC has low installation and maintenance costs. Additionally, PLC is capable of delivering high-speed data rates, as demonstrated in the HomePlug Powerline Alliance (HomePlug) and IEEE P1901 standards for home networking [2]. Due to these aforementioned advantages, PLC is contemplated as the most suitable ICT for smart grid communications, smart homes and buildings, smart vehicles, and smart cities [2]. Despite these benefits, PLC suffers from some challenges, such as varying impedance, strong branching effect, frequency and distance dependent attenuation, and non-gaussian noise [4]. On the other hand, PLC channels are intrinsically broadcast and ubiquitous in nature thereby widening the potential of an intrusion and making them more vulnerable to eavesdropping and jamming [5]. Therefore, offering unbreachable data security is always a significant issue in the PLC networks. Recently, physical layer security (PLS), also known as information-theoretic security, has been extensively studied by researchers in wireless and wired communication systems, where the randomness of the communication channels is exploited in the physical layer to prevent data leakage [3]. PLS is proclaimed as a complimentary approach to safeguard the data instead of entirely relying on traditional cryptographic algorithms. In this research, we investigate the PLS performance of a differential chaos shift keying (DCSK)-based PLC system by utilizing a novel Farlie-Gumbel-Morgenstern (FGM) Copula approach, where a wiretap power line channel model is analyzed to compute the secrecy between the main channel and the wiretap channel [6]. Both PLC channels are considered to be correlated Log-normally distributed while the Bernoulli-Gaussian model characterizes the PLC channel noise [7]. Further, the PLS performance is numerically expressed in terms of secure outage probability (SOP) and strictly positive secrecy capacity (SPSC). To obtain useful insights into the PLC system’s secrecy performance, the asymptotic SOP analysis is conducted. Furthermore, an algorithm is proposed to maximize the secrecy throughput under SOP constraints. Finally, meaningful observations are obtained by analyzing the impact of different system parameters through numerical results. Next, we analyze the PLS performance of PLC systems against multiple eavesdroppers by employing DCSK modulation scheme [8]. A wiretap power line channel model is investigated by considering two different cases: 1) when all the channels are assumed to be independent and identically distributed (IID) following Log-normal distribution; and 2) the wiretap channels are considered to be identical but correlated Log-normally distributed and independent of the main channel. Contemporaneously, the Bernoulli-Gaussian random process models the PLC noise. A comprehensive PLS study of the considered PLC system is characterized in terms of the average secrecy capacity (ASC), SOP, and SPSC. We also propose an algorithm to maximize the secrecy throughput under security and reliability constraints. Moreover, to obtain essential insights, we reveal the impact of various parameters onto the secrecy performance of the proposed PLC system. After studying the secrecy performance of the considered PLC system, this dissertation further evaluates the performance of the PLC systems under random pulse jamming attacks assuming M-ary phase shift keying modulation (MPSK) [9]. Herein, the PLC channel is assumed to follow Log-normal channel gain and the Bernoulli-Gaussian random process describes the nature of PLC noise. Additionally, the state of the jammer is characterized by the Bernoulli random variable. Conditioned upon the jamming activity, we evaluate the probability density function (PDF) of the instantaneous signal-to-jamming-plus-noise ratio (SJNR) and the instantaneous signal-to-noise ratio (SNR). Capitalizing on the statistical characterization of the SJNR and SNR, we derive the series-based expressions of the average symbol error rate (ASER) and outage probability (OP) for the considered PLC system. Further, the asymptotic ASER analysis is performed in terms of the coding gain and diversity order in the high SNR regime. In order to gain more insights into ASER and OP analysis of the considered PLC system, we demonstrate the effect of the different system parameters through the numerical results.Item Enhanced Edge Processing in Noisy Images: Leveraging noise-informed analysis for image denoising and edge detection(Indian Institute of Tehcnology, Jodhpur, 21-09-2024) Chouhan, RajlaxmiThis thesis aims to advance the research and development in image processing with a focus on edges of a noisy image by leveraging the noise itself. Edges occur where there is an abrupt change in the intensity in an image, and they act like boundaries or demarcations separating distinct objects in an image. Further, edges help enunciate the inner detailing present within an object. Since the very nature of edges is separating the boundary between two objects, it is highly desirable that the edges are definite and pixel-level accurate. Handling edges is challenging not only for developing an algorithm but also for extraction of ground truth. Some major contributions of this thesis include edge-preserving image denoising, enhanced edge detection, and modular plug-and-play edge post-processing. This thesis has also attempted to open new avenues by presenting how to analyze discontinuities (corners, lines, and edges) in real noisy environments, and how the noise (which is considered undesirable) can be used to improve the performance of a system at hand. The various analyses presented in this thesis go to the pixel-level details, with the objective to gain better insights that can be extended to diverse applications. Our first contribution deals with edge-preserving image denoising. It is well known that denoising through averaging typically reduces the sharpness of the edges and the details present in the denoised image. We proposed an edge-preserving image denoising algorithm where we extend the non-local means (NLM) algorithm by enhancing its most crucial part—the similarity weights. These similarity weights are enhanced, or in other words, rearranged, using the concept of stochastic resonance (SR). This iterative SR-based processing ensures that weights of similar patches are high and those of dissimilar patches are low. Through the lens of image attributes, the proposed work can be understood as iterative processing, and thereby enhancing, the similarity weights in a non-linear fashion using the modified and discretized Duffing’s equation. The proposed algorithm is tested for a wide range of AWGN noise, and benchmarked on the popular SET12 and BSD68 datasets. For a high noise (sd 50), the cumulative effect is reflected as an improvement (in PSNR) of 14.5% and 12.1% over that of NLM for SET12 and BSD68 datasets. As compared to the NLM, the proposed algorithm produces images with better visual quality, better edge preservation, and negligible artifact generation, especially at high noise. Our second contribution deals with discontinuity detectors and the noise behavior in real smartphone images. As smartphone cameras are the most popular photography devices in today’s era, we analyze how the discontinuity detectors like corner, line, and edge detectors behave when the image is corrupted by the real smartphone noise. On deeper analyses, it is observed and demonstrated that these discontinuity detectors exhibit SR in cameraphone noisy environment. The behavior of these detectors with changing noise as well with changing threshold is demonstrated. The pixel-level demonstrations presents how these detectors can take advantage of the presence of noise. Our third contribution is an application derived from the previous contribution and deals with improvement of popular Canny Edge Detector. Even the latest popular DL-based edge/boundary detectors produce thick grayscale edges (instead of thin binary edges), and struggle to achieve high pixel-level accuracy. Canny is a popular edge detector that gives thin binary edges, but it suffers from two major problems—broken edges and noisy structures. We propose an enhanced edge detector (SR-TW-CED) that improves the core of the Canny using SR-guided threshold maneuvering and window mapping. The whole image is partitioned into. windows, and mapped according to the underlying content, which decides how the threshold is to be maneuvered to obtain better edges. The proposed edge detector jointly addresses the two-fold problem of broken edges and noisy structures of the Canny edge detector. We also propose a novel measure of efficient edge detection; a unique, efficient way of edge content extraction and its combination for various channels; and a framework to handle repercussion of the randomness of the noise. Benchmarking on the BIPED dataset gives the human-level performance (F1 score 0.79), which is appreciable considering that it is a non-DL–based algorithm. Our fourth contribution is an application that derives its premise from the edge detection measures proposed in the previous contribution and does not directly use iterative SR processing. Most of the edge detectors in the research community are stand-alone edge detectors. With this contribution, we propose a post-processing filter that can simply be plugged in at the output of essentially any edge detector to suppress the detection of false edges, improve accuracy, and boost the precision of detection. A traditional edge detector suffers highly from false-positive edge detection, and the problem is so prevalent that the falsely detected edges often outnumber the true-positive detected edges. While this significantly limits the capabilities of non-DL–based edge detectors for typical images, it also creates a serious bottleneck in the performance of DL-based edge detectors particularly for images that contain texture or mesh. To address this, we have designed a novel framework, called the ’triple-window patch-debias broken-hysteresis’ framework. We also use the eigen-based measures as the filtering units in this framework to create a precision-boosting filter, called PBEdgeFilter. The proposed filter is a modular filter that requires minimum or, in most cases, no external inputs, and can be used in a plug-and-play manner. When tested on the BIPED dataset, PBEdgeFilter is observed to boost the precision of Canny by 89%, SMED by 102%, and LoG by 93.5%. When applied over the latest DL-based edge detector, DexiNed, the precision is observed to be boosted by 57.7% for the specific case of input images having mesh regions. The thesis includes image processing algorithms derived directly from or informed by the concept of SR or noise-enhanced iterative processing. While the first contribution, i.e. SR-enhanced NLM, directly utilizes the noise-aided iterative processing in a noisy environment, other contributions are broadly informed by the dynamics of signals (edges, in this case) in noisy and non-noisy environments. These contributions do not directly utilize SR-based processing but are designed with the rationale of signal behavior in different image regions. With the above contributions, an attempt has been made to contribute towards the knowledge base of edge processing in noisy environments.Item Cutting-Edge Consensus Algorithms in Scalable and Interoperable Blockchain(Indian Institute of Tehcnology, Jodhpur, 02-05-2024) Das, DebasisThe development of consensus algorithms is crucial for enhancing the scalability and interoperability of blockchain technology, which is key to its wider adoption. However, existing consensus algorithms, including Proof-of-Work (PoW), Proof-of-Stake (PoS), and Practical Byzantine Fault Tolerance (PBFT), face challenges such as high consensus delay, low throughput, and limited transaction scalability, primarily due to their high computational and communication complexity. Moreover, these algorithms rely on third parties to communicate across diverse blockchain platforms, making blockchain vulnerable, which emphasizes the necessity for interoperable solutions. In addition, ensuring information privacy within blockchain systems remains a significant challenge. Therefore, in this thesis, we develop novel consensus algorithms while focusing on improving consensus delay and throughput. The proposed modified Practical Byzantine Fault Tolerance (mPBFT) and Lightweight Consensus Algorithm (LCA) consensus algorithms are the improvement over the PBFT consensus protocol, which reduces the computation and communication complexity. The GridChain (a reputation based consensus algorithm) and Weighted Node Selection Byzantine Fault Tolerance (WNS-BFT) are the reputation and trust-based consensus algorithms that establish trust among the nodes while keeping the performance high. Additionally, to improve the performance further, we have developed a technique called BlockTree (a nonlinear structured, scalable, and distributed ledger) and UnoShard (Harmonizing Scalability and Security) schemes that address the issue of limited scalability by enabling the parallel processing of transactions. Furthermore, to address the interoperability issues between the diverse blockchain platforms, we developed a technique called CrossLedger (a pioneer cross-chain asset transfer protocol) that eliminates the presence of third parties for communication. This thesis has also addressed the issue of information privacy in the proposed technique called zk-SGB, a privacy-preserved blockchain framework for energy trading in a smart grid using zero-knowledge-proof (ZKP) without compromising system integrity. Next, this thesis discusses the various applications based on blockchain technology, such as the Internet of Things (IoT), Intelligent Transportation Systems (ITS), and Energy Trading in the Smart Grid. We have developed three schemes for IoT using smart contracts. The first scheme is a BLISS (Blockchain-based Integrated Security System for Internet of Things (IoT) Applications), and the second scheme is SCAB-IoTA (Secure Communication and Authentication for IoT Applications using Blockchain. We have implemented these schemes on the Ethereum blockchain testnet. Additionally, we have developed a testbed using Raspberry Pi devices to show the efficiency of the proposed scheme. Furthermore, we have developed two schemes for ITS. The first scheme is a LBSV ( Lightweight Blockchain Security Protocol for Secure Storage and Communication in SDN-Enabled IoV), and the second scheme is SmartCoin (A Novel Incentive Mechanism for Vehicles in Intelligent Transportation System Based on Consortium Blockchain). The LBSV and SmartCoin work on mPBFT and LCA consensus algorithms, respectively. Furthermore, we have also developed three schemes for the smart grid application. The first scheme is a SmartGrid-NG (Blockchain Protocol for Secure Transaction Processing in the Next Generation Smart Grid), the second scheme is an ETradeChain (Blockchain-Based Energy Trading in the Local Energy Market (LEM) Using a Modified Double Auction Protocol), and the third scheme is zk-SGB (Privacy-Preserved Blockchain Framework for Energy Trading in Smart Grid Using Zero Knowledge Proof). The first two schemes are focused on trading and transaction processing and work on GridChain and two-level consensus algorithms, respectively. The zk-SGB is designed to achieve privacy in smart grid transaction processing and works on the WNS-BFT consensus algorithm. A Raspberry Pi 4 Model B devices based testbed has been developed for the implementation of ITS and smart grid schemes.Item Device applications of specialty optical waveguides hosting exceptional points(Indian Institute of Tehcnology, Jodhpur, 29-09-2023) Ghosh, SomnathThe burgeoning field of non-Hermitian formalism in photonics has recently garnered considerable attention due to its capacity to unveil unconventional phenomena. Exceptional Points (EP s) within nonHermitian systems are particularly interesting, representing critical junctures where system behavior deviates significantly from the norm. EP s occur when coupled eigenvalues and corresponding eigenstates coalesce, leading to the collapse of the eigenspace-dimensionality of the underlying Hamiltonian. This collapse endows EP s with the characteristic of topological defects, and they have found applications in generating unique optical phenomena such as unidirectional lasing, enhanced sensing, asymmetric mode conversions, and optical isolation. This thesis explores EP s of various orders and investigates the resulting unconventional light dynamics in specialty planar optical waveguides with spatial refractive index variations and photonic bandgap waveguides. Customized planar optical waveguides and photonic bandgap waveguides featuring non-conservative elements like optical loss/gain are studied within a non-Hermitian framework to reveal topological avoided-crossing phenomena between coupled states/modes around specific singularities. The investigation delves into the intricacies of second-order, third-order, and fourth-order EP s within optical waveguides, uncovering unique mode excitation phenomena, chiral/non-chiral characteristics, and innovative methods for higher-order mode conversions. The study also extends to one-dimensional photonic bandgap waveguides, where the gain-loss processes enable precise control over TE modes through EP s. Dynamic encirclements around the EP lead to asymmetric mode conversions resilient to high fabrication tolerances. Conjugate EP s within dual-mode planar waveguides featuring T -symmetric optical potentials and complex refractive index profiles are explored. Reverse chiral response achieved through dynamic encirclements of a second-order conjugate EP s (EP2s) yields varying dominant modes dependent on encirclement direction. This concept is extended to a 1D photonic bandgap waveguide system, emphasizing robustness in the face of high parameter tolerances. Moreover, higher order conjugate EP s in two complementary systems have also been investigated, which leads to unconventional light dynamics by exploiting the time-reversal T symmetry. On the other hand, the dynamical encirclement of EP s in the presence of local nonlinearity has also been studied. By incorporating Kerr nonlinearity in the presence of gain-loss, optical waveguides are able to exhibit direction-independent mode conversion. Higher-order mode-collapsing phenomenon is observed during dynamical encirclements around higher-order conjugate EP s in multimodal complementary waveguides, offering the potential for one-way light transmission and intricate optical responses. This comprehensive exploration advances the understanding of EP s in photonics and their application in unconventional optical devices, paving the way for transformative developments in integrated all photonic components and devices for next-generation communication as well as emerging quantum technological applications.Item The Emergence of Inner Self-Experience: A Philosophical Inquiry into the Origin of Modern Self Conception(Indian Institute of Tehcnology, Jodhpur, 28-08-2023) Narayanan, V HariThe thesis is primarily an attempt to argue for the claim that human self-conception has undergone substantive changes over the course of human history. This goes counter to the position that human mentality remained the same since the origin of the species. Further, the thesis takes cudgels against the view that the inner, privately accessible world can be explained in terms of brain processes. The thesis argues that mere physical approach is insufficient for unravelling the origin of inner self-experience because we are ontologically unique and irreducible, and further inner self-experience is a matter of cultural and historical factors. This claim is called a modified form of liberal naturalism (Baker, 2013). It claims that entities such as the self are ontologically non-reducible to physical phenomena, and such phenomena emerge under certain conditions. The aim of the thesis is to shed light on the conditions required for the emergence of the inner self. It considers primarily (a) cultural and historical factors and (b) metaphorical language. Thus, the thesis argues that the modern-day self-conception is a later development in human beings rather than an innate biological trait accompanying our species since its dawn. The link between metaphorical language and developing an inner world is crucial because it might throw new light on the parallel development of language and the inner subject. Metaphors are not merely a matter of non-literal usage or a linguistic device; they structure and organize our psychological states in a ‘cognitive unconscious’ manner. (Lakoff & Johnson, 1980). The inner self is experienced as more than a physical thing. It is experienced as having multiple attitudes. Using propositional attitude establishes that the user understands itself as a subject. The nature of propositional attitudes, as complex intentional states, involve first-person concepts and, eventually, a robust first-person perspective. Therefore, the development of propositional attitude with metaphorical language is explored. To argue that there was a different mentality in the past from a phylogenetic perspective; Julian Jaynes's bicameral hypothesis has been used in its weaker sense. He proposes that a transition from a bicameral mentality to a self-conscious mentality took place with language sophistication and other factors. The thesis tries to extend a weaker version of the bicameral hypothesis cross-culturally by looking into an ancient Sanskrit text, namely RigvedaSaṃhitā. It analyses the linguistic usage with respect to the reference to the ‘self’ in the first twenty sūktas of it.Item Advanced and Emerging Materials for Energy, Environmental and Magnetic Applications(Indian Institute of Tehcnology, Jodhpur, 27-07-2023) Sharma, Rakesh Kumar; Singhal, RahulHarnessing a clean, affordable, and inexhaustible source of energy, its storage, and addressing environmental pollution necessitates extensive scientific attention. The depletion of these limited resources and their impact on the environment has motivated using alternative energy. Renewable energy sources are abundant and undependable. Renewable energy from solar and wind sources are irregular in nature, and diurnal and seasonal variations motivate the storage of renewable energy in a biomass-derived fuel, hydrogen, for later use. A greener, more attractive solution to this problem would be catalytic hydrocracking to produce biofuels and an electrocatalytic process to produce Hydrogen fuel. The main objectives laid out in this thesis are focused on the synthesis and engineering of materials with different morphological, structural, physical and chemical properties. The studies undertaken in this thesis attempt to address some of these issues. MXenes have a general formula of Mn+1XnTx, where M represents an early transition metal (Ti, V, Nb, Ta, Cr, Mo, etc.), T refers to the surface terminating functional groups such as oxygen, fluorine, and hydroxyl group, X represent C or N and n= 1, 2 or 3. MXene was synthesized in 2011 by the selective etching process of the Al from the MAX phase. This material exhibits remarkable properties such as metallic conductivity, hydrophilicity, redox activity, good dispersibility, and photochemical stability. Our study includes bandgap engineering of ZnOMXene for Photocatalytic pollutant degradation and electrocatalytic hydrogen evolution reaction. The maximum photodegradation efficiency was demonstrated by the 10 wt % ZnO- Ti3C2 composite, which degraded the methylene blue (MB) dye by 76.4 % within 10 minutes of the reaction and by 99.2 % within 60 minutes. Excellent HER performance was demonstrated by the 5 wt % ZnO-Ti3C2 nanocomposite with overpotential of 495 mV at 10 mA/cm2 and a Tafel slope of 108 mV/dec. Herein, Ti3C2Tx and ZnO-Ti3C2Tx catalysts were also demonstrated for selective hydrodeoxygenation reaction (HDO) of methyl oleate (MO) as the model compound. The synthesized ZnO- Ti3C2Tx catalyst showed 100% conversion of MO with >90% selectivity for HDO product (n-C18). Additionally, the pure Ti3C2Tx demonstrated 100% conversion with a selectivity of 67% for n-C17 hydrocarbon via the decarboxylation route.3 As a part of sustainable energy production, thesis work also focuses on solvent-free bio-jet fuel generation (C8 to C15) from the model substrate methyl oleate as well as various oils feedstocks (Linseed, Rapeseed, Neem and Tung oils) using Fe-loaded SiO2-Al2O3 as solid acid catalyst. The acidic sites rendered by the Fe metal and SiO2-Al2O3 support reveal that the catalyst is suitable for low pressure hydrocracking of methyl oleate into bio-jet fuel with excellent selectivity (>74 %) and complete conversion at 380°C, 5 bar H2 pressure with 10% iron loading in five hours. Additionally, the magnetic properties of LMO (lithium manganese oxide) and Gd-doped LMO were correlated with each other. The magnetic properties can easily identify the minor variations that SEM, TEM, FITR, and XRD cannot detect. Therefore, magnetism is also one of the essential tools for material properties. As a result of the Mn+2 or Mn+3 ions being replaced by Gd+3 ions from the octahedral 16d lattice location, the samples displayed a paramagnetic (at 300K) to antiferromagnetic (at 5K) transition and fluctuation in the magnetic moment. The superexchange process is revealed to be responsible for the phase changes that were detected in the hysteresis curve below the Neel temperature (TN) at 5K.Item Open Volumetric Air Receiver based Solar Convective Furnace System(Indian Institute of Tehcnology, Jodhpur, 30-06-2023) Chandra, Laltu; Mukhopadhyay, SudiptoElectrical energy from fossil fuels or gas-fired systems is commonly used as a heat source for industrial process heating, such as the heat treatment of metals, which leads to harmful emissions. Freely available solar energy is a viable option for transitioning to a net zero carbon economy and reducing emissions. For instance, harnessed solar energy with a concentrated solar thermal (CST) system may be utilized, for example, in the melting, coating, and joining of metals. Recently, a novel, retrofitted solar convective furnace (SCF) system was developed for the heat treatment of Aluminum using hot air from a heliostat-based CST system. The developed SCF system comprises an open volumetric air receiver (OVAR), two pebble-bed sensible thermal energy storage (TES) systems, viz. primary and secondary, and the furnace itself. The OVAR produces hot air using the concentrated solar irradiance onto its aperture. The generated hot air is transported to the SCF directly or indirectly via the primary TES. The secondary TES is utilized for waste heat recovery from hot air at the furnace outlet. The feasibility assessment of the SCF system is performed using a two-step approach: (1) experiments are performed for each of the sub-systems and the integrated system, and (2) mathematical models are developed for scaling of OVAR, each of the sub-systems, and the integrated system analysis. The details are described as follows: Parametric experimental investigations are performed with primary TES for charging and discharging processes to evaluate its thermal evaluation. The experimental investigations for primary TES showed that the time-averaged charging and discharging efficiencies are 65-70% and 72-75%, respectively. Further analyses revealed the exergy efficiencies for charging and discharging are 45-50% and 58-60%, respectively. Experiments are performed to investigate heat transfer in the retrofitted solar convective furnace. These experiments include a provision for external heating for SCF. Experimental results of SCF, such as temperature profile and heating process, show the capability of heat treatment of metal-ingot via forced convection. For the numerical design, OVAR size (a key component of SCF) is selected based on a preliminary calculation for 0.58 MW capacity Aluminum furnace, with direct normal irradiance (DNI) of 220 W/m2 and a concentration ratio of 600. The modelling of unsteady heat transfer in OVAR is done by considering multiple zones of the receiver, viz. central, intermediate, and peripheral zones. The model was validated with experimental data and a two-zone model, which demonstrated the model's prediction capability within ±7%. A parametric investigation is carried out for the planned scale up OVAR design. An unsteady heat transfer model is developed for the TES. Analysis revealed that the deviation between the computed and experimental temperature is within ±15%. Also, a one-dimensional mathematical model is developed to analyze the unsteady heat transfer process for the retrofitted SCF. The calculations show a deviation of about ±15% from the experimental data. Finally, a mathematical model is developed for the installed lab-scale SCF system, including OVAR, connecting pipes with insulation, and TES. Findings demonstrate the potential of using the developed CST-based SCF system for the heat treatment of metal. However, the integrated model needs to be refined for better results and may be addressed in future.Item Simultaneous Wastewater Treatment and Generation of Value-added Products in Photosynthetic Microbial Fuel Cells(Indian Institute of Tehcnology, Jodhpur, 23-01-2024) Chhabra, MeenuDwindling fossil fuel reserves, increasing population, market volatility, and ecological repercussions have driven the need to develop alternative energy sources and efficient wastewater treatment systems. Photosynthetic Microbial Fuel Cells (PMFCs) emerge as a multifaceted solution, combining wastewater treatment, power generation, and valuable microalgae biomass recovery for potential biofuel applications within a single framework. Researchers have enhanced PMFC performance by refining electrodes, cathode catalysts, reactor design, and optimizing anodic bacteria to facilitate efficient electron transfer. However, widespread industrial adoption of PMFCs still needs to be improved. To amplify the potential of PMFC-based microalgae biorefineries, selecting a cathodic strain that bolsters power output and yields high-value products (like carotenoids) is pivotal. In this context, our initial study identified a suitable microalgae strain, Chlamydomonas reinhardtii, boosting power generation efficiency (15.31 W/m3) in PMFC when operated at 100 ml working volume in a fed-batch mode. Moreover, this strain yielded high-value microalgae biomass enriched with pigments, antioxidants, and antibacterial properties against known pathogens. Subsequently, the C. reinhardtii strain was Genetically Modified (GM) to enhance carotenoid biosynthesis by exogenous expression of two critical genes, β-carotene ketolase and β-carotene hydroxylase from Hematococcus pluvialis, through nuclear transformation. The resultant GM algal lines exhibited a remarkable 5.39-fold increase in β-carotene production and showed astaxanthin production. Further, this Wild Type (WT) and GM C. reinhardtii were tested for MFC application at lab-scale reactor of 100 ml working volume in a fed-batch mode. GM microalgae didn't compromise MFC performance, while β-carotene production escalated 2.49 times compared to the WT microalgae. Collectively, this strategy overcomes significant challenges by generating alternative energy sources and producing high-value carotenoids, presenting an economically viable biorefinery approach.Item Design, Development, and Characterization Studies of Non-Thermal Non-Equilibrium Plasma Systems for Indoor Air Quality(Indian Institute of Tehcnology, Jodhpur, 29-07-2024) Prakash, RamAccording to the world health organization, air pollution is one of the top 5 risks causing chronic diseases, and airborne transmitted pathogen infection is a huge challenge. In the modern era, indoor air pollution has become a complex issue involving various contaminants that harm human health. Furthermore, the rise of multidrug-resistant pathogens (ESKAPE bacteria) within the clinical environment presents a mounting problem in hospitals worldwide. The available indoor air purification methods do not effectively address long-living pathogens and small-size aerosols. In this context, a few dielectric barrier discharge (DBD) based portable cold-plasma devices have been designed and developed. The optimized source has been studied for its disinfection efficiency in the indoor environment of sizes up to ~ 28.3 m3. The developed source comprises a coaxial DBD configuration with a specially designed wire mesh structure acting as a ground electrode. The need for feed gas, pellets and/or differential pressure has been eliminated from the plasma sources. The device is able to produce active air ions predominantly dominated by hydroxyl radicals (•OH) in the indoor environment similar to Mother Nature, which disrupts bacterial cell structures and metabolic processes. The existence of active air ions for more than 25 seconds on average is the key advantage, which can also deactivate long-living pathogens and small-size aerosols. One of the electrodes of the plasma source has been coated with TiO2 nanoparticles for the efficient production of active air ions and •OH. The operating parameters such as applied voltage and frequency has been optimized on the basis of active air ions, •OH, and ozone (O3) generation. The deactivation efficiency of total bacterial counts (TBCs) and total fungal counts (TFCs) has shown more than 99% in 90 minutes of continuous operation of the device at the optimized parameters. The complete inactivation of MS2 phage and E. coli bacteria with more than 5 log reductions (99.999%) has been achieved within 30 minutes and 90 minutes of device operation in an enclosed environment. In just 60 minutes of device operation, more than 99.9% ESKAPE bacterial inactivation has also been achieved. The mechanism underlying bacterial inactivation by active air ions and •OH has been discussed. A similar source for high efficiency volatile organic compounds (VOCs) degradation has been tested for the decomposition of toluene and benzene in an enclosed environment of ~ 0.34 m3. For about 60 minutes of continuous source operation, a decomposition efficiency of 99.7% (toluene) and 74.8% (benzene) has been achieved. Furthermore, the on-site generation of •OH has been confirmed by the chemical actinometrical method and is basically due to the highly energetic electrons (3 – 5 eV) and active air ions from the DBD plasma source. To comprehend the analysis, another study examining the impact of varying relative humidity (RH) using a surface dielectric barrier discharge (SDBD) plasma source has been carried out. The effect of RH on the discharge parameters is discussed in detail. The results show that, even with the same peak-to-peak applied voltage, the peak-to-peak current and discharge power decrease with increasing RH. Instead of UV radiation, the plasma-produced highly energetic electrons activate the TiO2 nanoparticles for electron-hole pair generation, and the same has been confirmed using X-ray photoelectron spectroscopy. From the developed DBD plasma source, the airborne microorganism’s disinfection efficiency of ~ 95.8% and ~ 98.7% has been achieved in the TBCs and TFCs at an RH range of 70% – 90% in just 20 minutes of continuous operation. However, in the RH range of 20% – 40%, the inactivation efficiency dropped to ~ 78.8% and ~ 87.5% for the TBCs and TFCs, respectively. The outcome indicates that higher humidity levels are better for indoor air purification using the developed source and that plasma with a circulation system can effectively disinfect indoor environments. Development and demonstration of efficient cold plasma sources in this thesis for indoor air purification at the lab scale is a significant achievement with promising future scope. More efforts are needed to implement cold plasma sources in the actual conditions, to inactivate several airborne viruses, including SARS-CoV-2 and the MS2 phage, in order to establish this as useful technology for the general public.Item Development of DBD Plasma-based UV-C Excimer Light Sources for Health and Environmental Applications(Indian Institute of Tehcnology, Jodhpur, 15-07-2024) Prakash, RamTo render unwanted or harmful microorganism’s incapable of reproducing, the ultraviolet light is very useful in our daily life. Ultraviolet (UV) light is a spectrum of light just below the range visible to the human eye. The UV light is divided into four distinct spectral areas, and they are Vacuum Ultraviolet (VUV) (100–200 nm), UV-C (200–280 nm), UV-B (280–315 nm) and UV-A (315–400 nm). These spectral areas are very specific. The UV-C radiation from 200–280 nm is highly useful to inactivate a wide range of microorganisms based on DNA absorption capacity in this range. This spectral range can be further utilized in advanced oxidation processes (AOPs) to generate reactive species like hydroxyl radicals (•OH) to oxidize organic and inorganic contaminants in water and wastewater. When we look for the real-life problems, wastewater discharged from the textile industry contains approximately 15% unfixed dyes, predominantly 60–70% azo dyes, which pose significant environmental and health risks due to their persistence and potential toxicity. Also, organic micro-pollutants (OMPs) have become common causes of pollution and have attracted considerable attention in recent years due to their extensive environmental consequences. To mitigate the issue, in the recent decades, dielectric barrier discharge (DBD) plasma-based excimer/exciplex sources are being researched in generating UV-C (230–280 nm) and far UV-C (200–230 nm) light radiations. This thesis work is focused on the design, development and optimization of cylindrical and planar excilamps emitting different wavelengths in UV regions for health and environmental applications. In the present work, DBD plasma-based far UV-C (KrCl*) and an advanced UV-C (XeI*) excilamps with a very narrow and intense spectrum peaking at a wavelength of 222 nm and a wide band 253 nm, respectively, have been developed and used for the health and environmental applications. Two types of DBD geometries, i.e., planar and coaxial, have been worked out. In this context, the optimization of high-voltage electrodes has been carried out to minimize lamp heating without any external cooling. The main reason for the controlled heating is the homogenous discharge at low gas pressure and the helical moulded copper wire electrode with optimized pitch. These lamps are optimized for higher efficiency. Due to the confined gas gap and bi-polar pulse power arrangements, the spectra obtained from far UV-C (KrCl*) are very narrow, having a full width half maximum (FWHM) of 1.7–1.9 nm. The electrical to optical conversion efficiency for this lamp is found to be ~12.5% and complete inactivation of S. aureus and E. coli bacteria with initial control ~ 107 CFU/ml is achieved at a UV dose of 3 mJ/cm2 and 12 mJ/cm2, respectively. In furtherance to it, the optimized XeI* and KrCl* excilamps are utilized for the treatment of wastewater, mainly containing azo dyes and OMPs by direct photolysis or in combination with AOPs (i.e., excilamp/TiO2 and excilamp/H2O2). An advanced process is developed in which one electrode of XeI* excilamp is coated with the photocatalyst, improving the Reactive Black 5 (RB5) mineralization efficiency. The result confirms 13 times faster degradation in XeI*-excimer/H2O2 than XeI*-excimer/TiO2, attributed to an abundance of •OH generated by the modified XeI*- excimer/H2O2. A maximum energy yield of 5712 mg/kWh is reported in the case of XeI*- excimer/H2O2. Compared with 254 nm, RB5 shows 1.26 times higher molar absorption at 222 nm. The obtained energy yield (6565 mg/kWh) for excimer-222/H2O2 demonstrates that the process is efficient in terms of energy consumption. In one of the studies, non-thermal plasma (NTP) has been integrated with KrCl* excilamp to eliminate the use of chemicals and simultaneously enhance OMP degradation. Plasmaproduced nitrates (𝑁𝑂3-) and hydrogen peroxide (H2O2) have been utilized for the generation of •OH when exposed to KrCl* excilamp. The degradation rate of different OMPs is found to be several times higher under plasma + KrCl* excilamp compared to plasma + LPUV due to the generation of the abundance of •OH (46.7 × 10-8 M s-1) under KrCl* from 𝑁𝑂3- and H2O2 present in the water matrix. This is due to the higher molar absorption of 𝑁𝑂3- and H2O2 at 222 nm than 254 nm. This plasma coupling with KrCl* excilamp outperformed all the other methods regarding OMP degradation. Development and demonstration of efficient far UV-C radiation (222 nm) sources in this thesis for different applications at the lab scale is a significant achievement with promising future scope. More efforts are needed to implement far UV-C radiation sources in the actual conditions, with potential advantages for environmental sustainability, public health, and technological innovation.Item Rejuvenation of Proteostasis Defects Based on Proteasomal Functions Regulates Improper Cellular Proliferation and Induces Misfolded Proteins Clearance(Indian Institute of Tehcnology, Jodhpur, 14-07-2024) Mishra, AmitProteostasis is an essential process ensuring the optimal functioning of proteins and cellular homeostasis, involving maintenance of synthesis of proteins, their folding, and degradation by cellular protein quality control (PQC). Failure of PQC machinery, including chaperones and the ubiquitin-proteasome system (UPS), can lead to protein misfolding and disturbed cellular proteostasis. The consequent misfolded protein accumulation can form the basis of neurodegeneration onset and largely represents imperfect aging. Understanding how cells rejuvenate deregulated PQC mechanisms to maintain proteostasis and prevent the aggregation of normal proteins by misfolded inclusions is a major challenge. The present work demonstrates that lanosterol, an intermediate in cholesterol synthesis pathway, enhances proteasome proteolytic activity, thereby supporting the PQC mechanisms for eliminating intracellular aberrant proteins. Moreover, lanosterol exposure promotes the clearance of both bona fide proteins and toxic proteins linked with neurodegenerative diseases. In contrast, many cancer cell types have higher proteasomal expression as well as activity than normal cells. Designing of novel proteasome inhibitors and targeting proteasome machinery for therapeutic purposes emerged as a promising molecular strategy for restricting the cancer cell proliferation. Valproate, an approved drug for treating seizures, is a class I histone deacetylases (HDACs) inhibitor and an attractive chemotherapeutic agent for targeting cancer. Few reports suggest that valproate can suppress cell growth and cell differentiation and is linked with antitumor activity. However, valproate-associated anti-tumoral function and intracellular signaling cascade-mediated anti-cellular proliferation activities are still not completely known. This current study indicates that treatment of valproate inhibits proteasome activities and also aggravates the accumulation of expanded polyglutamine proteins and other proteasomal substrates. Moreover, inhibition of proteasome by valproate also induced mitochondrial dysfunction and apoptosis. Overall, our finding elucidates the potential of valproate as a proteasome inhibitor, which can be beneficial in combination with other anti-tumor agents for more effective therapeutic interventions.Item Investigating various Aspect of Neutrino Non-Standard Interaction(Indian Institute of Tehcnology, Jodhpur, 31-10-2023) Sinha, MonikaThe Standard Model (SM) of particle physics is by far the most successful theory of the fundamental interactions of nature. But still, it cannot be considered the ultimate theory as it fails to accommodate gravity, dark matter and dark energy. This motivates us to look for beyond Standard Model (BSM) physics. Neutrinos, in particular, provide an elegant platform to probe such BSM physics. The neutrino oscillation (NO) experimental data can be explained within the context of the SM framework. However, in the light of upcoming high precision experiments,neutrinos have immense potential to analyze the BSM physics which is popularly known as nonstandard interaction (NSI). In this thesis, I study various facets of NSI and analyze the effect of NSI in several physical systems. The repercussion of NSI is possible to be observed at the lower energy scale such as the terrestrial neutrino accelerator or reactor experiments which operate within the energy range ∼MeV-GeV, as well as in the ultra high energy (UHE) regime (≳ EeV). We study the effect of vector type NSI on the shower events generated by UHE neutrinos detectable by neutrino telescopes such as the IceCube observatory. The UHE neutrinos arrive at Earth originating from different sources of cosmic accelerators and initiate deep inelastic scattering (DIS) with the nucleons present inside the Earth. Such interactions are capable of producing microscopic black holes (MBH)if the Universe consists of large extra spatial dimensions which also consequently gives rise to TeV scale gravity. These MBHs quickly decay producing a large number of shower events. We find that in the presence of vector type NSI, the large number of shower events clearly indicates the signal of TeV scale gravity. In the domain of lower energy domain, we analyze the effect of vector NSI on the various measures of temporal and spatial correlations present in the three flavour neutrino system, which exhibit the entanglement embedded in the system and are directly related to the neutrino oscillation probability, in the context of long baseline (LBL) accelerator experimental setup DUNE. We find that for the LMA-Dark solution of vector NSI, the temporal correlation quantified in terms of Leggett-Garg type Inequality (LGtI) shows violation at the energy corresponding to the maximum flux observable at DUNE. The spatial correlations involved in this study, the flavour entropy and genuine tripartite entanglement also exhibit significant deviation in the presence of NSI as compared to the result obtained for the SM."Item Mitigation of Weldability Issue and Residual Stresses in Dissimilar Welded Joints of Ultra-Super Critical Power Plants(Indian Institute of Tehcnology, Jodhpur, 19-03-2024) Pandey, ChandanThe growing demand for electricity can be fulfilled by either installing more and more number of power plants or by improving the output of existing power plants by increasing its efficiency. The installing of more number of power plants leads to the overall increase in generation of greenhouse gases like CO2, CH4, and NOx. The efficiency of the power plant depends on the operating conditions, i.e., temperature and pressure. The increase in operating temperature by 10 oC results in an increase in the efficiency of the power plants by 0.5 %. To operate the power plant at elevated temperature and pressure, the demand for the material with high creep rupture strength, high thermal conductivity, and high corrosion resistance increase significantly. The most commonly used material in power plants operating at high temperatures and high pressure are creep strength enhanced ferritic (CSEF) steel, austenitic stainless steel (ASS) and nickel-based super alloys. CSEF P91 steel was developed to sustain at extreme operating conditions of ultra-supercritical (USC) power plants, and later, P92 was developed to achieve better mechanical properties, higher creeprupture strength and high operating temperature with the reduction in wall thickness as compared to P91 steel. The most common application of P92 material in power plants includes high pressure and high-temperature steam piping, headers, and water-wall tubing. The other most commonly used material in the power plants is austenitic stainless steel, i.e., SS 304L. The austenitic grade stainless steel offers high resistance to corrosion due to the high wt. % chromium and nickel content (18–20 and 8–12, respectively). Due to the low carbon content, the 304L is less sensitive to the sensitization problem and offers excellent weldability. The joining of these dissimilar materials is frequently required in the power generation industry. The different chemical composition, mechanical, physical and metallurgical properties of the CSEF P92 and 304L austenitic grade stainless steel leads to the problems such as carbon migration and high welding induced residual stresses at the weld. The nickel-based filler wire is frequently used due to its intermediate physical and mechanical properties. The gas tungsten arc welding (GTAW) process was used to join the P92 and 304L with various filler metals like ERNiCrMo-3 (INCONEL 625), ERNiCr-3 (INCONEL 82), ERNiFeCr-2 (INCONEL 718) and Thermanit MTS 616 (P92 filler). The X-ray radiographic examination and macrostructure analysis confirmed the decent quality of the P92/304L weld joint. From the comparison of the V-groove and narrow groove geometry, it was found that the narrow groove requires less filler metal than the conventional Vgroove geometry. Also, a narrow groove geometry significantly reduces heat affected zone (HAZ) width due to less heat input. The overall welding induced residual stress was also less for narrow groove geometry. After welding, a substantial change in the microstructure and mechanical properties of the P92 HAZ was noticed. However, the microstructure and mechanical properties of the 304L remain unaffected. The post-weld heat treatment (PWHT) is required to eliminate the heterogeneous microstructure during the dissimilar welding. The microstructure of the weld fusion zone confirmed the formation of secondary phases due to the segregation of various alloying elements at the end of the solidification. The energy-dispersive X-ray spectroscopy (EDS) result showed that these secondary phases were enriched with molybdenum (Mo), chromium (Cr), and niobium (Nb). Micro-hardness study revealed that hardness of P92 coarse grain heat affected zone (CGHAZ), and fine grain heat affected zone (FGHAZ) was higher than P92 base metal after welding due to the formation of untempered martensite. After PWHT micro-hardness of CGHAZ, FGHAZ was decreased due to the tempering effect. The inter-critical heat affected zone (ICHAZ) was the weakest region before and after PWHT. The tensile study reveals that 304L was the weakest link in P92/304L dissimilar weld joint. The specimens were broken from the 304L in as-welded and PWHT condition. Both the P92 steel and weld fusion zone was safe in as-welded condition and PWHT condition. The impact toughness value of the ERNiCr-3 weld region was observed to be higher than the other nickel- based filler metal like ERNiCrMo-3, ERNiFeCr-2, and ERNiCrMoCo-1 (INCONEL 617). It is because of the high nickel (Ni) and low iron (Fe) content in the ERNiCr-3 filler metal. The tensile strength was evaluated at 450 oC, 550 oC, 650 oC, 750 oC, and 850 oC temperature to examine the performance of the dissimilar weld joint at elevated temperatures. After high-temperature tensile strength, the creep performance of the P92/304L dissimilar weld joint has also been investigated at 650 oC in the stress range of 80-200 MPa. All the creep specimens failed from the P92 steel base metal region during the creep test at different conditions. The coarsening of various precipitates such as M23C6 carbides, MX carbonitrides, and formation of laves phase influence the mechanical property, and creep-rupture strength of dissimilar weld joint.Item Investigations on Dissimilar Metal Welding for Marine Applications(Indian Institute of Tehcnology, Jodhpur, 12-04-2024) Chhibber, Rahul; Pandey, ChandanDissimilar metal welds are prevalent in marine and offshore structures, posing risks of substantial financial, material losses, and potential threats to human safety in case of joint failures. Dissimilar metal welding involves scientific and technical challenges and is commonly employed in the offshore construction, oil and gas, marine, and petrochemical sectors. Erosion and corrosion in marine environments can cause significant damage to offshore and marine structures, prompting cost-effective solutions such as the replacement of critical components. Enhancing the structural integrity of marine and offshore structures requires the use of dissimilar metal welding to join steels and alloys with different mechanical and chemical properties. However, challenges such as carbon migration, unmixed zones, heterogeneity, cracking, and intermetallic phases must be carefully assessed before implementation in industrial applications. The primary focus of this study is on dissimilar welds involving high-corrosion-resistant super duplex stainless steel (sDSS 2507) paired with nitronic steel (N50), nickel-based superalloy (IN-625), and pipeline steel (X-70). The dual-phase sDSS 2507, with balanced austenite and ferrite phases, is known for excellent mechanical properties and corrosion resistance. Nitronic steel is widely used in subsea oil and gas tubes and couplers due to its superior tensile strength, corrosion, and galling resistance. Nickel-based superalloy (IN-625) finds applications in marine, aerospace, and petrochemical sectors owing to its high tensile, yield, and creep strength, as well as corrosion resistance in harsh environments. Pipeline steel (X-70) is employed in deep-water industries for tubing/tubing-coupler assemblies, subsea manifold piping systems, marine splash zones for drilling risers, and branching/subbranching in oil-gas distribution pipelines, driven by economic considerations and its exceptional tensile and impact strength. A multi-pass gas tungsten arc welding process will be employed to fabricate dissimilar weld joints (DWJs) using different overmatching fillers, heat input, and welding parameters, aiming to highlight the structure-property relationship and ensure structural integrity. The study investigates different facets of the welds of these dissimilar joints, including microstructure evolution, mechanical characterization, residual stress measurement, wear resistance, and corrosion behavior. Electron probe microanalysis will reveal the weld interface alloying element gradient. The investigation extends to assess the impact of heat input and filler metal composition on the residual stress, wear, and corrosion behaviors of these dissimilar joints. The deep hole drilling technique is employed to measure through-thickness residual stresses in the weld zone, mitigating the risk of catastrophic marine component failure. Sliding wear behavior is investigated under dry conditions to replicate realworld service environments for sDSS 2507/N50 DWJs, while slurry pot erosion behavior is investigated at varying slurry concentrations to simulate actual service conditions for sDSS 2507/IN-625 DWJs and sDSS 2507/X-70 DWJs. The joints are examined for corrosion resistance using immersion and electrochemical corrosion methods. This thesis aims to improve the structural integrity of marine and offshore structures in the transportation and oil and gas exploration sectors by providing insights into material selection, optimal welding parameters, heat input for weld fabrication, and design optimization.Item Study and Implementation of Millimeter Wave Antenna and Arrays using Substrate Integrated Coaxial Line (SICL) Technology(Indian Institute of Tehcnology, Jodhpur, 31-01-2024) Mukherjee, SoumavaWith the exponentially increasing traffic in the wireless radio communication, there is a continuous need for wide frequency spectrum to meet the demands of faster communication. The next generation wireless technology (5G & beyond) is a plausible solution capable to support the demands of increasing data rates and accommodate the constantly increasing traffic by exploiting larger bandwidth. It is predicted that by 2030 or sooner the cellular communication industry is going to adopt 5th generation (5G) standards. According to the Friss transmission line equation, the path loss at such high frequencies become prominent as compared to microwave frequencies. Hence, the challenge exists for designing the RF front end, especially antennas at millimeter wave frequencies with broad bandwidth and high gain. The well-known microstrip technology becomes lossy at high frequency due to the generation of surface waves and radiation losses of the unbounded microstrip line. Large waveguide-based antennas were considered initially for operation in 5G millimeter wave (mmwave) range. In past decade many novel technologies have surfaced in the planar form that enables designing light-weight RF circuits in compact form factor. The bounded Substrate Integrated Waveguide (SIW) technology reduces the surface and radiation losses but supports narrowband single mode operation. Substrate Integrated Coaxial Line (SICL) is an emerging and promising candidate with self-shielded structure that removes the drawbacks incorporated in these existing technologies. SICL is the planar implementation of rectangular coaxial line that supports single broadband TEM mode of propagation. The radiation losses in SICL are minimized compared to the microstrip and stripline technology. Additionally, SICL provide wideband unimodal TEM operation, which is not achievable in SIW technology. The work proposed in this thesis focusses on design and implementation of microwave and millimeterwave antennas and arrays using SICL technology. Firstly, dipole antenna-based designs are developed to achieve wide bandwidth. Certain design techniques are followed to realize broadband dipole antenna and wideband quasi-Yagi antenna, bow-tie antenna. SICL based cavity backed slot antenna (CBSA) is designed and developed at mmwave frequencies in much compact footprint while exhibiting high front-to-back ratio (FTBR) and polarization purity. To deploy the antennas for 5G mmwave applications, high gain antenna arrays are developed. Novel crossed dipole antennas and half mode SICL cavity-based antenna arrays are proposed that exhibit wide band performance to meet the requirements of 5G communication. Further, reconfigurability in bandwidth, polarization, direction, etc. has been achieved in the antenna using diodes, switches, etc. These antennas and arrays are designed to cover the 3GPP n257, n258 and n261 FR2 bands that make them suitable for practical 5G deployment. To establish a satisfactory link of the end users with the access point, 360° beam coverage is achieved in SICL based MIMO antenna arrays (for upcoming 5G/6G) with high isolation performance. Lastly, a MIMO array with novel feed line is designed that supports simultaneous 10/28 GHz transmission for futuristic 5G & beyond communication. SICL is expected to become a popular attractive candidate for designing antenna arrays especially where small form factor is preferred as in modern hand-held devices and customer premises equipments (CPE).Item Redox-active Phenalenyl-based Transition Metal Complexes for Applications in Resistive Memory Device and (Electro)Catalysis(Indian Institute of Tehcnology, Jodhpur, 29-01-2024) Metre, Ramesh K.In the last couple of decades, the frontiers in synthetic inorganic chemistry have been pushed in a new direction, aiming to reduce the utilization of Earths less abundant or noble metal resources. Such a path toward the environment sustainability began with the innovative approach of identifying base metal ions that can be strategically combined with redoxinteresting ligand systems. The coordination of a redox-active ligand helps the coordinated base metal ions to survive unfavorable oxidation states and retain overall stability during the chemical reactions. The introduction of redox-active ligands facilitates the uninterrupted multielectron transfer, stabilizes the electron-deficient transition states, and can successfully tune the single electron metal-centered redox changes. Therefore, the molecules with superior redox activity are important charge carriers and can be implied as active materials or catalysts for various applications. In this regard, we have carefully functionalized the phenalenyl-d ligands for a variety of sustainable applications. Phenalenyl (PLY) refers to an odd alternant polycyclic hydrocarbon that has shown the potential to exist in three energetically favorable redox states, i.e. cation, anion, and radical. The cationic form of PLY can be readily generated via metal coordination, which can accept electrons to form stable PLY-based radical and anionic species. The work in this thesis highlights the coordination chemistry approach for the synthesis of PLY-based metal complexes, their extensive characterization and the applications varying from resistive memory device to (electro)catalysis. In Chapter 3, we discuss a square planar [CoIIL] complex, which was prepared from a PLY-based ligand, LH2 = 9,9-(ethane-1,2-diylbis(azanediyl))bis(1H-phenalen-1-one). The interesting solid-state packing analogous to the charge transfer salts present in this complex motivated us to explore its application in solidstate resistive memory device. Chapter 4 covers the synthesis of square planar [IIL] complex, which is employed as a catalyst for the oxidation of polycyclic aromatic hydrocarbons. The Chapter 5 of the thesis highlights the synthetic modifications of PLY architecture to design ligands that can give rise to dinuclearity in the resulting metal complexes. We prepared two dinuclear Fe(III) complexes, [FeIII2(hmbh-PLY)3] and [FeIII2(hnmh-PLY)3] from hmbh-PLYH2 = 9-(2-(2-hydroxy-3-methoxybenzylidene)hydrazineyl)-1H-phenalen-1-one and hnmh-PLYH2 = 9-(2-((2-hydroxynaphthalen-1-yl)methylene)hydrazineyl)-1H-phenalen-1-one ligands, respectively. Both complexes are explored for the electrochemical H2O2 reduction and employed as cathode material in one-compartment H2O2 fuel cell. In Chapter 6, we discuss the synthesis of a dinuclear Ni(II) complex, [NiII2(dtbh-PLY)2] from 9-(2-(3,6-di-tert-butyl-2-hydroxybenzylidene)hydrazineyl)-1H-phenalen-1-one, dtbh-PLYH2 ligand and its electrocatalytic behaviour in the oxygen evolution reaction (OER).Item Exploring Physic Beyond the Standard Model: Flavor and Neutrinos(Indian Institute of Tehcnology, Jodhpur, 06-03-2024) Alok, Ashutosh KumarThe Standard Model (SM) of electroweak interactions offers the most precise depiction of nature at the fundamental level. However, it falls short of being the quintessential theory of nature, as it does not account for phenomena such as matter-antimatter asymmetry of the universe, dark matter, and dark energy. This necessitates a search for physics beyond the SM. We concentrate on flavor and neutrino physics as avenues to explore potential new physics. Flavour physics, especially involving B meson decays, offers a promising avenue to uncover physics beyond the SM. Recent Large Hadron Collider (LHC) experiments at CERN have provided numerous measurements in b → sℓℓ (ℓ = e, μ) transitions, drawing attention due to their intriguing deviations from the SM predictions. The most striking discrepancy lies in the measurement of the branching ratio of Bs → ϕμ+μ− decay, which disagrees with the SM at the level of 3.5σ. The core concept involves investigating the underlying Lorentz structure of new physics, which provides a better fit to current b → sℓℓ data as compared to the SM and then looking for implications of these favored patterns in other related sectors. In order to determine the Lorentz structure of new physics, we performed a model independent global analysis of all b → sℓℓ data within the framework of effective field theory. We subsequently implemented these favored scenarios in a variety of Z′ models, both heavy (TeV scale) as well as light (MeV scale). It was observed that these models adeptly accommodate the current b → s measurements. Further, the impact of b → s measurements on rare charm decays was explored in a non-universal Z′ model where ui → uj transitions can be induced by Z′bs and Z′μμ couplings along with suitable combinations of the CKM matrix. Constraints on Z′ couplings from b → sℓℓ, ΔMs, and neutrino trident data revealed that significant enhancements beyond the SM are not viable. We then investigated the implications of CP conserving b → sℓℓ measurements on the amount of CP violation allowed in B → (K, K∗)μ+μ− decays. For statistically favoured solutions with universal complex couplings, we obtained predictions for various CP violating observables and also examined correlations between them, which provided effective discriminators for new physics solutions. We also considered the impact of b → sℓℓ (ℓ = e, μ) measurements on possible new physics in b → sτ+τ− sector under a framework where both universal and nonuniversal couplings are present. We analyzed several observables in B → K∗τ+τ− decay along with a number of lepton flavour universality violating (LFUV) observables in τ − μ sector. It was observed that the current data allows for deviations from SM spanning from 25% up to even orders of magnitude in several observables. Further, we found that the ratios Rτμ K and Rτμ K∗ diverge from SM even in the presence of only universal new physics scenarios. We also suggested methods to discriminate between these two classes of solutions. Finally, we constructed genuine LFUV observables in the τ −μ sector through an analysis of the full angular distribution of these decays. The flavor systems can also be used to investigate physics emerging from much finer length scales such as quantum decoherence. We devised a formalism using the Kraus operator method to investigate how quantum decoherence affects B meson observables. Through the analysis of purely leptonic, semileptonic, and non-leptonic decays of B mesons, we identified observables that could be influenced by decoherence. Considering that many of these observables can be measured with high precision using the abundant data collected by LHCb and Belle II, our formalism can be applied to establish constraints on the decoherence parameter through multiple decay channels. This offers an alternative set-up for such studies, which, at present, are predominantly conducted in the neutrino sector.The measurements in the flavor sector can have far reaching consequences, for e.g., specific new physics models which can accommodate the current measurements in B sector can also generate neutrino magnetic moment. This electromagnetic property of neutrino offers a unique window into physics beyond the SM. Neutrinos may possess non-zero magnetic dipole moments(μν) due to quantum effects at the loop level. This cannot only serve as clear indicators of new physics but can also have far-reaching implications in particle physics, astrophysics, and cosmology. Due to this generation of the magnetic moment, neutrinos can exhibit spin-flavor oscillations (SFO) in the presence of an external magnetic field. Also, several studies predict the existence of a primordial magnetic field (PMF) in the early Universe, extending back to the era of Big Bang nucleosynthesis (BBN) and before. The recent NANOGrav measurement can be considered as a strong indication of the presence of these PMFs. For Dirac neutrinos, we show that half of the active relic neutrinos can become sterile due to SFO well before becoming non-relativistic owing to the expansion of the Universe and also before the timeline of the formation of galaxies and hence intergalactic fields, subject to the constraints on the combined value of μνB and the cosmic magnetic field at the time of neutrino decoupling. For the upper limit of PMF allowed by the BBN,this can be true even if the experimental bounds on μν approach a few times its SM value. Furthe, we also investigate quantum coherence in neutrino SFO within the interstellar magnetic field of the Milky Way and beyond, quantified by the l1 norm and the relative entropy of coherence. We find that for flavor oscillations, coherence measures can sustain higher values over distances of several kilometers, relevant for terrestrial experiments like reactors and accelerators whereas for SFO, the coherence scale can extend to astrophysical distances.Thus, it becomes apparent that our investigations have yielded pivotal results that hold relevance within the diverse spheres of particle physics, astroparticle physics, cosmology and even Planck scale physics. This overarching theme showcases the interconnectedness and far-reachingimplications across these multifaceted sectors. The exploration of connections between pertinent measurements in particle physics, astroparticle physics, and cosmology is especially vital, given that experiments in all these domains are currently on the cusp of entering a precision era.Item Cu₂HgSn(SeₓS₁₋ₓ)4 Based Quaternary Chalcogenides for Photovoltaic and Thermoelectric Applications(Indian Institute of Tehcnology, Jodhpur, 22-08-2024) Dixit, AmbeshNumerous theoretical and experimental investigations on multinary Cu-based compound semiconductors have followed the successful materialization of chalcogenide-based energy devices. This work aimed to identify the potential energy applications of the Cu2HgSn(SexS1-x)4 compound by investigating its composition with x= 0, 0.25, 0.50, and 1. The bandgap tunability is observed to be between 0.81 to 1.33 eV for whole composition, according to the electronic structure calculations. Its excellent ductile strength and substantial absorption coefficient of around 104 cm-1 across all compositions reveal its promise as a flexible optoelectronic device working in the visible-to-infrared spectrum. Considering realistic material parameters such as defect concentration, doping concentration, and interface effect, device modeling for single/tandem junction and graded bandgap absorber-based photovoltaics suggests that the grading bandgap absorber-based device could be the best option for maximizing efficiency by harnessing the maximum solar spectra. Our research shows that a 2m thick absorber performs well when the concentration of Se increases rapidly towards the back contact side, allowing for positive bandgap grading in the absorber. According to our findings, the device's efficiency is maintained up to a bulk defect density of 1015 cm3. However, it is extremely susceptible to interface defects, which diminish its performance even after a concentration of 1012 cm2. A substantial efficiency may be achieved with a positive conduction band offset of approximately 0.3 eV, which inherently provides a large built-in field at the junction and helps the device extract the photocarrier effectively with an efficiency of over 20%. We have also investigated the material's thermoelectric potential in detail by studying the phonon dynamics of Cu2HgSnS4 in the intermediate temperature range, with special emphasis on the role of the heavy element Hg substitution in the parent compound Cu2ZnSnS4. Our overall lattice thermal conductivi 0.53 W m-1 K-1 (0.33 W m-1 K-1) at 300 K (700 K), when we account for both the particle and wave-like phonon treatments. The heavy metal mercury introduces a small amount of anharmonicity, and its significant vibrational amplitude is comparable to the rattling mode in compounds with a cage-like structure. As a result of extremely low thermal conduction, the highest possible ZT value for a p-type (n-type) system is 2.28 (0.77), suggesting that it might be used for thermoelectric applications at intermediate temperatures. This study could help experimental efforts to design graded bandgap absorber-based photovoltaics as well as serve as a guide for intermediate temperature thermoelectric devices using quaternary chalcogenides or Diamond Like Semiconductors.