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Lightweight Block Cipher Optimizations for Resource Constrained Applications
No full textThe work presented in the thesis is broadly in the domain of optimization of lightweight cipher architectures. The S-box optimization problem, the side-channel countermeasure problem for mitigating side-channel attacks, along with one resource-constrained application use case for the healthcare sector, form the focus of the work reported in the thesis. Resource-constrained applications are often involved in handling sensitive data and communicating with each other and end-users, necessitating security requirements. This calls for the encryption architectures to be lightweight. Further, optimising lightweight ciphers for hardware has been less explored, which opens the scope for research in this field. The motivation of choice for the selected research problem stems from the fact that the domain of lightweight cryptography is relatively less established. With increasing IoT devices becoming part and parcel of daily lives, trading off security and performance gains importance. The detailed analysis of different lightweight ciphers indicates that proposed architectures have better design and performance metrics with acceptable trade-offs. The proposed architectures are catered to meet resource-constrained application design and performance constraints. The implementation platforms, i.e. FPGA or ASIC, also influence the architecture’s resource utilization. In general, the speciality of the proposed optimized architectures is that they can apply to all the symmetric block ciphers, whether lightweight or conventional crypto algorithms. The thesis’s contribution begins with optimizing S-box architectures for lightweight ciphers. Initially, three S-box architectures have been proposed utilizing the logic synthesis approaches. The techniques include the reuse of minterms technique, which is a gate based approach, and the multiplexers-based implementation of the S-box architectures. The gate-based approach was observed to have utilized lesser area with a trade-off for delay. The MUX-based architectures have been more beneficial because they map efficiently with the FPGA resources, reducing the number of slices, without increasing the delay of the architectures. The next part of the thesis deals with the optimization of S-box architectures utilizing functional decomposition techniques. This includes six techniques utilizing the one and two variables decomposition, frequent variable elimination, Binary Decision Diagram, positive Davio expansion, and another hybrid method combining the latter and Shannon’s Decomposition methods. The architectures implemented based on these techniques include the multiplexers, gates, and/or a combination of both. The S-box architectures implemented using the techniques have been incorporated into the overall encryption architectures of PRESENT, Midori, KLEIN, GIFT, and RECTANGLE lightweight ciphers. The complete architectures have been evaluated on the FPGA platform with a 13.56 MHz frequency suitable for RFID applications and 2.45 GHz for ISM band applications. The S-box architectures are also evaluated for SAED90nm standard libraries to validate it for ASIC realization.The S-boxes implemented with the proposed techniques have resulted in optimized outcomes in terms of area, power and delay. The S-boxes have been included in the overall cipher architecture and proved to be better than the state-of-the art architectures. These results are tailor-made to meet the design specifications for IoT enabled devices, which have not been investigated earlier to the best of our knowledge. Apart from the S-box architecture optimizations, the thesis contributes to the datapath optimization of the substitution permutation network. In this regard, PRESENT and Midori lightweight cipher have been experimented with. The proposed architectures are so designed that the delay and power consumption of the designs have been significantly reduced compared to the 64-bit datapath. The low power metrics have been achieved by adding power-efficient selector modules, which reduce the dynamic power consumption of the overall architecture for both FPGA and ASIC platforms. The thesis also proposes the side-channel countermeasure using masking techniques with fewer overheads than existing techniques. The compact and high throughput architecture of Midori, designed earlier, inculcates a masking feature to make it resilient against side-channel power attacks. The proposed masking technique results in fewer overheads when compared with the existing masking methods. The last part of the thesis looks into the applicability of the proposed architectures to resource-constrained applications in a healthcare setup. The encryption and decryption processes of the Fitbit dataset have been illustrated. An encryption decryption model is illustrated using the proposed S-box architectures with associated trade-offs
Removal of Organic Dyes and Arsenate Ions from Contaminated Water Using Synthesized Nitrate‐ Intercalated Mg2Al and Zn2Al Layered Double Hydroxide Nanoparticles
No full textThe study primarily focuses on maximizing the adsorption capacity of the synthesized nitrate intercalated Mg2Al and Zn2Al layered double hydroxide (MA-LDH and ZA-LDH) nanoparticles for adsorption of anionic dyes and arsenate [As (V)] ions through the application of the Box-Behnken Design (BBD), and the Hybrid Design (HD), respectively within the framework of Response Surface Methodology (RSM). Highly crystalline nitrate intercalated MA-LDH and ZA-LDH nanoparticles were synthesized using the traditional co-precipitation technique under reflux conditions in the nitrogen atmosphere in the particle size range between 100-150 nm and 250-300 nm, respectively. For adsorption of the methyl orange (MO) and acid yellow-36 dye (AY) onto the MA-LDH and ZA-LDH nanoparticle, various parameters such as the adsorbent dose (5–20 mg), the incubation time (3–60 min), the temperature (25–50 °C), the pH of the dye solution (5–9), and the dye concentration (0.03– 0.1 mg/ml) were examined in the batch adsorption process for optimization of the conditions for maximizing the adsorption capacity using the BBD. Adsorbent dose was optimized after suspending different amounts of dose such as 5, 10, 15, and 20 mg in 50 ml water containing 0.03mg/ml dye concentration for 60 min. After that, the optimized values of the incubation time, temperature, and pH were found to be 25.89 min, 35.99 °C and 5.16, for the dyes onto the MA-LDH, whereas for ZA-LDH nanoadsorbents the corresponding values were found to be 52.4 min, of 35.45 °C, 5.75, respectively. The adsorption kinetic at different temperatures and isotherm at 40 ˚C for the adsorption of the dyes onto the MA-LDH and ZA-LDH were well fitted with pseudo- second-order kinetic model and Langmuir model, respectively. According to the Langmuir isotherm, the maximum adsorption capacities exhibited by MA-LDH were 583.109 mg/g MO and 412.55 mg/g AY dye, and those for ZA-LDH were found to be 601.62 mg/g MO and 462.48 mg/g AY dye indicating monolayer chemisorption mechanism in these cases. MA-LDH retained up to 78.4 % MO and 70.35% AY dye adsorption capacity, whereas those values for ZA-LDH were found to be 72.3% of the MO and 60.43% of the AY dye after five cycles of regeneration. A Hybrid Design (H.D) was used to optimize the four independent variables, such as adsorbent dose (5–15 mg), arsenate concentration (5–20 ppm), temperature (25–50 °C), and incubation time (25–120 min) for maximizing the arsenate adsorption capacity onto the as mentioned LDH nanoparticles containing aqueous suspension. The optimized values of the adsorbent dose, adsorbate concentration, temperature, and incubation time were found to be 10 mg, 12.25 ppm, 37.90 °C, and 72.5 min for adsorption of the As(V) ions from its aqueous solutions. The adsorption kinetics and isotherms for the adsorption of As(V) ions onto the MA-LDH and ZA-LDH nanoadsorbents were well fitted with the pseudo-second-order kinetic model and Langmuir model, respectively. According to the Langmuir isotherm, the maximum adsorption capacities exhibited by MA-LDH and ZA-LDH were 216.80 mg/g and 219.42 mg/g, respectively. Up to the five cycles of regeneration, the MA-LDH and ZA- LDH nanoadsorbents retained an adsorption capacity of 54.45% and 40.83% of maximum As(V) adsorption, respectively. Thermodynamic parameters, such as a high negative value of ΔG and positive value of ΔH suggested that the adsorption process was spontaneous and endothermic in nature. Layered Double Hydroxide (LDH) nanoparticles show promise for removing industry excreted hazardous anionic species from waste water. Future applications could involve developing novel LDH based compositions with high surface area, enhanced regeneration potential, enabled with feasible separation techniques and sensing platform to be tested under real-world condition to validate their effectiveness in large-scale industrial waste water treatment
Design and Development of Various Virtual Oscillator Control Techniques for Parallel Inverters in Standalone Microgrid
No full textIn recent times, renewable energy sources (RES) have been used as potential alternatives to conventional generation systems connected to the grid. The power electronic inverters are the principal media of interface for integrating the RES into the utility grid system. This work is primarily focused on the different virtual oscillator control (VOC) strategies such as Deadzone oscillator (DZO) based VOC, Van der Pol oscillator (VdPO) based VOC, and Andronov-Hopf oscillator (AHO) based VOC for the parallel inverters in a standalone Microgrid (MG). The well-known droop control method for parallel inverters emulates only the droop characteristics of the synchronous machine. Virtual synchronous machine (VSM) is also a familiar control method for parallel inverters. It emulates not only the droop characteristics of the synchronous machine but also the swing equation. Therefore, VSM has a remarkable difference in the dynamic performance of the system compared to the droop control method. The droop and VSM control methods need measurements of both voltage and current. In addition, the calculation of active and reactive power requires low-pass filters (LPFs). Typically, LPFs have low cut-off frequencies that restrict the controller bandwidth. The slow dynamic response, real and reactive powers interaction, sensitive performance with line impedance and non-linear loads, etc., are still evident drawbacks despite the many modified methods to improve the droop and VSM control methods. However, the VOC works on instantaneous feedback signals so that it achieves much faster synchronization and better power-sharing. The idea of the proposed VOC is to control an inverter such that it emulates the behavior of nonlinear oscillators. Compared to droop and VSM techniques, the VOC can achieve faster dynamic response and is easy to implement. It also does not require inner control loops, trigonometric functions, and LPFs. The selection of control parameters in DZO based VOC is difficult and time-consuming by using conventional method. Hence, they are designed by using different optimization techniques such as Particle Swarm Optimization (PSO), Sine Cosine Algorithm (SCA), modified Sine Cosine Algorithm (mSCA), African Vulture Optimization Algorithm (AVOA), and Artificial Jellyfish Search Optimization (AJSO). The MATLAB/Simulink simulations are carried out to examine the performance of the system with the conventional DZO based VOC and the aforesaid optimized DZO based VOC such as VOC-PSO, VOC-SCA, VOC-mSCA, VOC-AVOA, and VOC-AJSO. In comparison to all control methods, the VOC-AJSO is observed to achieve faster synchronization. The effectiveness of the suggested VOC-AJSO control approach is also proved by the experimental results. In the traditional VOC methods such as DZO and VdPO based VOC, there is always the presence of a third-order harmonic in the output voltage, which causes a significant amount of third-order harmonic current in the system. The nonlinear dynamical equations of the oscillator are analyzed, and its nonlinear current source is made simpler in order to develop New-VdPO based VOC for parallel inverters that can effectively get rid of the third-order harmonic component in the oscillator’s output voltage. Finally, an extensive comparison of DZO, VdPO, and a New-VdPO based VOC methods with linear and nonlinear loads is presented. Simulation results of the DZO, VdPO, and the proposed New-VdPO based VOC methods with different loads (resistive, linear RLC, non-linear) are compared and analyzed in detail. The third-order harmonic is dominant in both DZO and VdPO based VOC methods whereas it is very less in the New-VdPO based VOC method. Hardware experimentation is also carried out to analyze the efficacy of the proposed New-VdPO based VOC method for parallel inverters in standalone MG. The results clearly depict that the New-VdPO based VOC strategy is quite efficient in handling the output voltage harmonics. In the DZO, VdPO, and New-VdPO based VOC methods, the output voltage falls as the load increases, which might be problematic for sensitive equipment that demands a constant voltage. This work proposed a fuzzy logic algorithm (FLA) based adaptive VOC methods (DZO-Adaptive, VdPO-Adaptive, and New-VdPO-Adaptive) to eliminate this limitation. The proposed New-VdPO-Adaptive based VOC controller has good voltage regulation and lower total harmonic distortion (THD). The computational and experimental results of the proposed control schemes are presented and compared to other control methods to determine the effectiveness of the proposed adaptive control schemes. The limitations of DZO and VdPO based VOC methods are limit cycle restrictions, stability issues due to initial conditions, and guaranteed synchronization conditions. The AHO based VOC method does not need to consider the limit cycle restriction or the rigorous adequate synchronization requirement and provides improved power quality. The parameter selection of AHO is quite complex because the speed constant and AHO capacitor have a greater range of values. To minimize these limitations, the mSCA based optimization approach is proposed for choosing the AHO parameters. The objective of this is to reduce the settling time of the inverter output voltage during startup and the peak overshoot as a constraint. Finally, the proposed optimized AHO (OAHO) method can give better performance than the other aforesaid control methods in terms of initial response time and THD. Finally, the above-mentioned control techniques are applied to three-phase parallel inverters in standalone MG. When compared to the aforesaid control approaches, the proposed OAHO based VOC method can provide superior performance. The significant works have been carried out in this dissertation: (a) the detailed implementation of various VOC methods (DZO, VdPO, and AHO) for parallel single-phase and three-phase inverters in standalone MG, (b) different optimization techniques are used to improve the existing VOC methods, (c) proposed a FLA based adaptive VOC methods to eliminate the voltage regulation issues in the conventional VOC methods, (d) overall performance of the proposed VOC methods has been evaluated in computational and experimental platforms
Cloud Microphysical Processes of Tropical Cyclones Over Indian Seas: Impact on Size and Intensity Changes
No full textTropical cyclones (TCs) are natural catastrophic phenomena and the destruction is mostly determined by their movement, intensity, and radial expansion of winds (size), etc. It is essential to have an accurate forecast of these TC traits to lessen the damage to lives and property in coastal regions. In recent decades, a noticeable improvement in the TC track prediction. However, fewer improvements are noted in TC intensity, and little attention was paid to size predictions over the North Indian Ocean (NIO) basin. The TC size and intensity changes are multiscale problems, interacting with both synoptic-scale and vortex-scale processes. Hence, insights into responsible physical and microphysical (MP) processes for size and intensity changes help to improve TC predictions. The thesis started investigating the inter-relationships between size parameters (radius of maximum wind, Rmax; 34-knots wind, R34; and TC-fullness, TCF) and intensity over the NIO. Intensity is found to have a relatively stronger correlation (0.7) with TCF when compared to that with R34 (0.5) and Rmax (0.6). Analysis shows that size changes are weakly correlated with intensity changes (0.37-0.39). Diagnostic analysis has been conducted to address possible reasons for different relationships between size and intensity. For this, TC samples are categorized based on the linear regression coefficient (LRC) between size and intensity evolution. The average LRC of Group–1 to Group–4 are 1.42 km/knots, 2.18 km/knots, 2.7 km/knots, and 3.62 km/knots, respectively. The dry air intrusion in outside the eyewall and low vertical wind shear conditions in Group–1 TCs limit rain-bands development, and support to no/smaller size increases with intensity. In Group 2, Strong surface fluxes in the primary eyewall region support convection and absolute angular momentum (AAM) at upper and lower levels. It leads to increases in size with intensity. Strong and broader surface fluxes and vertical velocities may create rain-bands or secondary-eyewall in Group–3. It supports to enhance the size with limited intensification. In Group–4, larger initial TC vortices maintain wider and more intense surface fluxes, vertical velocities, and AAM in inner-core and outer-core regions of TC. These are favorable to maintaining larger sizes than the remaining groups. In a follow-up study, the impact of MP processes and horizontal grid resolution on TC size is analyzed. TC movement is less sensitive to MP schemes, while the size is more sensitive. The simple-ice scheme produced smaller TCs (R34) due to less MP-heating caused by the evaporation of rainwater and lesser efficiency of freezing. Due to the absence of ice treatment and more rainwater, the warm-rain scheme produced a larger TC size. The size simulated from other schemes is more or less the same. Analyses indicate that higher MP-heating induces intense vertical velocities, and AAM and thus increases the TC size. In addition, finer model resolution results in smaller TC sizes. For any particular resolution, the simulated size differs by 30–50 km among the MP schemes, while the size changes by 5–15 km (2–4 km) between 6 km and 2 km (3 km and 2 km) grid-resolutions for any MP scheme. The study concludes that better TC size can be achieved with appropriate MP schemes at higher/cloud-resolving grid resolution. Results indicate that the inner-core heating is strongly correlated with the precipitated compared to non-precipitated hydrometeors. Furthermore, the vertical distribution of hydrometeors and heating is dependent on inner-core updrafts and relative humidity. A novel composite analysis of microphysical processes indicates that the warmer inner core is close to saturation with excess water vapor, which enhances the latent heat release (LHR) through condensation below the freezing level during the rapid intensification (RI) onset. In addition, during RI, strong updrafts transport the liquid hydrometeors above the freezing level and enhance the LHR because of deposition and freezing respectively. The increased precipitating particles in the saturated inner core also enhance LHR. The symmetric convection structured by the atmospheric moisture causes the formation of prolonged RI episodes, as seen in TC Phailin. During rapid weakening (RW), asymmetric and relatively fewer hydrometeors are evident, along with the presence of weak updrafts and strong shear. The dry-air intrusion into the inner core also causes the cooling processes (evaporation and sublimation). The enhancement or reduction of moist static energy and potential vorticity is associated with increased or reduced LHR in the TC rapid intensity changes. Assimilation of INSAT-3DR thermodynamic profiles provides improved initial conditions for the WRF model. Improved initial conditions help improve intensity in 23 cases (out of 36 cases). The track errors are improved by ∼10%, intensity (10 m max surface winds) by 22%, and MSLP by 28%. The mean errors indicate that the maximum (95th percentile) error in the INSAT run is almost close to the mean error of the CTL run. The quantitative verification indicates that the INSAT detects 42% of rapid intensification and 18% of weakening cases. The INSAT experiment exhibits 14%, 21%, and 12% improvement in mean size (R34, R50, and R64) simulations, respectively. Overall, it can be concluded that the INSAT run improved the distribution of RH around the TC center, adjusting MP-heating/warm-core through precipitable and non-precipitable hydrometeors. Thus, the tangential and radial winds are improved. This study highlights the credibility of INSAT profiles on TC size and intensity, particularly intensity changes. The present thesis provides better insights into cloud microphysical processes controlling changes in TC characteristics, particularly TC size and intensity changes over the NIO basin
Modification of Structural Steel Surface Using Plasma Sprayed Nickel-Titanium Alloy
No full textSolid particle erosion (SPE) is a material removal process in which high-speed solid particles continuously hit the target material and erode its surface. Due to material erosion, the surface faces various effects such as surface roughening, decreased functional life span and degradation of components. Atmospheric Plasma Spraying (APS) is one of the most commonly used coating techniques, which comes under the thermal spraying process. It has a wide range of applications due to its versatility in surface modifications. By the APS technique, different high-temperature application materials like cermets, ceramics, etc., can be coated. Ni50Ti50 (at.%) smart alloy became more focus of interest for researchers and industrialists due to their two extraordinary properties such as shape memory effect (SME), and superelasticity (SE) behaviour. This alloy also gives good wear resistance, corrosion resistance, damping behaviour, and high load-bearing capacity. In terms of mechanical properties, it has high strength and hardness at high temperatures. Due to the above properties, NiTi alloy can be used to protect structural materials such as mild steel from catastrophic failure. In the current research, structural steel such as mild steel, stainless steel and Domex 700 MC steel have been coated at different substrate preheating temperatures by APS techniques using equiatomic NiTi alloy. The main objective of this research is to investigate the physical, mechanical and tribological properties including the investigation of phase, microstructure, porosity, deposition efficiency, surface roughness, microhardness, adhesion strength, erosion behaviour and its correlation. Surface and interface analysis has been done using SEM, XRD, Hardness test and Optical profilometer. The surface morphology of the coatings confirmed the number of unmelted particles decreases gradually with increases in substrate temperature. Interface morphology indicates the gradual decrease in percentage of pore with an increase in substrate temperature. Phase analysis shows the presence of required phases NiTi along with some intermetallics such as Ni4Ti3, Ni3Ti and oxide phases on the sprayed surface. Various intermetallics and dense morphology contributes higher hardness of the coating interface that increases with an increase in substrate temperature. Compressive residual stress was calculated at the coating surface having successive splat layers for the investigation of mechanical properties of the sample. Microstructure and densification helps to improve the strength of fabricated parts. At 400°C preheating temperature coating shows higher cohesive bond strength as compare to lower preheating temperature due to better mechanical bonding between the splats at higher preheating temperature. The NiTi APS coated mild steel substrate shows better features as compare to stainless steel and Domex 700 MC steel substrate in terms of adhesion strength, deposition efficiency, and interface property
Design and Development of a Mechanical Peeler Cum Decorer and Value-addition of Kadamb (Neolamarckia Cadamba) Fruit
No full textKadamb fruit (Neolamarckia cadamba) is an underutilized tropical fruit belonging to the family of Rubiaceae and has traditional therapeutic and functional properties including its tree leaves, flowers, roots, and bark. The post-harvest minimal processing for removal of peel and seed to get the edible core of the fruit is done manually which is laborious, time-consuming, cause injury to the person, and may cause contamination. The operations for washing, peeling, coring, and seed removal are designed as a continuous automated machine for optimum utilization of the kadamb fruits and to reduce these traditional process problems. Hence, the physical, structural, and textural properties of the fruit have been investigated for the design of the machine. The fruit comprising functional groups like antioxidants, polyphenols, and anti-bacterial compounds can be used in other foods to increase their nutritional value. The proposed machine was designed using CATIA V5 software (R2013, CAD, USA) and fabricated which will be economically and commercially feasible for farmers, and small and medium-scale industries. The equipment consists of a feed hopper, processing chamber, water spray system, and outlet for edible core and waste. The performance of the equipment was evaluated, and the process parameters such as feed rate and speed were optimized. The optimum peeling efficiency of 74.26% and coring efficiency of 75.64% was achieved at a 63.22 kg/h. feed rate and speed of 210 rpm. Processing time, cost, and quality of edible core were better than that of the manually produced core suggesting the feasibility and proper working of the peeler-cum-decorer. The cost economic analysis of the equipment was also done. The unit cost of the machine was Rs. 25,000.00 INR. The return on investment (ROI) of 169%, breakeven point (BEP) of 4759 kg of edible core production, and payback period (PBP) of 216 days on the initial investment cost suggest the economic feasibility and commercial viability of the equipment. The cost of processing was Rs.3.07 INR against Rs.24.44 INR per kg in manual method. The developed machine could be a possible solution for processing and value-addition of kadamb fruits for increasing the income for sustainable livelihood of rural population dependent on the collection and sale of fruits. It could also help in commercializing kadamb fruit products for use in the food and herbal medicine industry. Value addition of matured and ripe kadamb fruit was also done in the form of pasta and candy, respectively which showed good sensory properties
Use of Remote Sensing Data in Assessing the Impact of Climate and Land Use Land Cover Change on Groundwater Dynamics in Semi-Arid Regions
No full textThis study examined how Land Use Land Cover (LULC) and climate affect groundwater dynamics in Southern India's semi-arid region (Chitravathi River basin) and identified the suitable sites for constructing the artificial recharge structures using geographical information systems (GIS). Coupled Model Intercomparison Project Phase6-Global Circulation Models (CMIP6-GCMs) climatic data is used to generate climate projections for the future. The GCMs are ranked for precipitation and temperatures using the Taylor Skill Score (TSS). Rating Metric (RM) was preferred to establish the final rank of the GCMs. Ensemble of projections from the top four ranked GCMs (MPI-ESM1-2-LR, EC-Earth3, MPI-ESM1-2-HR, and INM-CM5-0) were used as they estimated the most reliable forecasts for all the three considered parameters. MPI-ESM1-2-LR was the top-ranked GCM with an RM of 0.92. By using the ensemble GCMs, the six extreme precipitation indices, namely, consecutive dry days (CDD), consecutive wet days (CWD), total wet-day precipitation (PRCPTOT), R10mm (days), R95p (very wet days in mm), RX1day (maximum 1-day precipitation in mm) were calculated as per Expert Team on Climate Change Detection and Indices (ETCCDI) recommendations. Trend analysis of all the above parameters was calculated using Mann-Kendall (MK) and Spearman's rho tests. The future LULC map was produced using cellular automata and artificial neural networks (CA-ANN). Using standard modelling techniques, the SWAT model was used to evaluate the individual impact of climate change on groundwater recharge and the combined impacts of LULC and climate change. The SWAT model was calibrated for discharge data on a monthly basis at a gauging station. The overall accuracy of the SWAT was R2 = 0.83 and NSE = 0.81. The SWAT groundwater module estimates recharge for baseline (1985 - 2014), near-future (2015 - 2030), mid-future (2031 - 2060), and far-future (2061 - 2100) under the moderate SSP2-4.5 and extreme SSP5-8.5 emission scenarios. MODFLOW steady-state groundwater flow model was employed to predict future groundwater levels. Calibration of the model was performed based on seasonal groundwater level data spanning the years 2014 - 2022, and validation was carried out using data from 2020 - 2022. MODFLOW model exhibited good overall accuracy, with R2 values of 0.96 during calibration and 0.94 during validation. Based on the projected groundwater recharge and levels, a resiliency map of the basin was developed. Results revealed that recharge during constant LULC conditions ranged from 135 to 215 mm/year under SSP2-4.5 and 149 to 316 mm/year under the SSP5-8.5 scenario. Compared to baseline recharge (116.4 mm), the future groundwater recharge under both SSPs increased. The results also indicated that by the year 2060, under the SSP2-4.5 scenario, groundwater levels in the basin would decrease by 54 m, while under the SSP5-8.5 scenario, the decrease would be 62 m. By 2060, both SSPs indicate poor groundwater resiliency. Observations from the study highlight the non-resilient state of groundwater. In response, a study was conducted to identify locations conducive to artificial recharge of the groundwater system. Using remotely sensed data and GIS tools, thematic maps incorporating soil type, geology, topography, and groundwater information were overlaid. The Weighted Overlay Analysis (WOA) with assigned weighted scores and the Analytical Hierarchy Process (AHP) identified favourable sites for groundwater recharge. The resultant map guides the spatial distribution of these sites, offering valuable insights to safeguard and sustain the basin's groundwater resources
Performance Enhancement of Serverless System
No full textServerless computing has emerged as a transformative paradigm in cloud computing, offering scalability and cost efficiency by abstracting infrastructure management. This thesis presents a holistic investigation into serverless computing, focusing on three key contributions: performance and cost modeling, performance and cost optimization, and event-driven state management. In the first contribution, it addresses the limitations of existing performance and cost models by introducing an analytical model that accommodates complex application structures such as loops, self-loops, parallel paths, and cycles. This model, applied to serverless workflows, provides an accurate estimation of end-to-end response time and cost. Traditional resource allocation models are inadequate for serverless platforms, which charge based on actual resource consumption. To bridge this gap, it develops an efficient predictive cost model that considers parameters such as execution time, memory usage, and function invocation patterns. Optimizing performance and cost in serverless computing is essential for achieving an optimal balance between resource utilization and economic viability. A greedy-based optimization algorithm is proposed to determine the optimal memory configuration, achieving the best response time within budget constraints. This algorithm explores trade-offs between performance optimization and cost minimization, considering the dynamic nature of serverless environments. The cold-start problem, a significant challenge in serverless computing, is addressed in the second contribution. An integrated adaptive model is introduced that leverages the LSTM-based deep learning approach to predict future workloads, minimizing both the frequency and delay of cold starts. The proposed efficient container placement module accelerates container delivery, and a high-performance serverless containerization prototype optimizes cold-start delays by grouping similar functions. The third contribution focuses on state management, a critical aspect of serverless computing. An event-driven state management strategy is proposed that aligns state changes with triggering events, ensuring a scalable and natural approach to managing state in serverless architectures. This approach enhances reliability and efficiency, addressing the challenges of maintaining state in the transient and dynamic nature of serverless environments. This thesis advances the understanding of serverless computing through a comprehensive study of performance modeling, optimization, and state management. The proposed models and strategies contribute to overcoming existing research gaps, providing valuable insights for practitioners and researchers. The findings underscore the significance of balancing performance and cost while addressing challenges such as the cold-start problem and state management in serverless computing
Establishment of Caprine Pancreas Derived Extracellular Matrix as a Novel Reservoir to Develop Xenotransplantable Organ and Scarless Wound Healing Hydrogel
No full textThe quest for biomimetic scaffolds with enhanced regenerative potential in tissue engineering has led to the exploration of natural extracellular matrices (ECMs) derived from various sources. This thesis focuses on investigating the potential of the caprine pancreas-derived ECM as a promising biomaterial for tissue engineering and regenerative medicine applications. Commencing with the isolation and characterization of decellularized Caprine pancreatic ECM using several detergents, the aim was to identify the best decellularization method. Upon decellularization, the ECM of different tissues responds differently to the detergents used for decellularization at a physical and physiological level; hence the impact of decellularization by ionic (SDS and SDC), non-ionic (Triton X-100, and Tween-20), and zwitterionic detergents (CHAPS) was first analyzed via immersion and perfusion decellularization. The mode of decellularization (i.e., immersion and perfusion) was discovered to significantly impact the final scaffold quality, in addition to detergents. It was observed that perfusion decellularization yielded a significantly superior scaffold compared to immersion decellularization across all evaluated aspects, including residual DNA content (SDS, SDC, CHAPS, Tw-20, and TX-100 had 17.43 ± 1.18 ng/mg, 0.83 ± 0.31 ng/mg, 3.86 ± 0.32 ng/mg, 2.95 ± 0.11 ng/mg and 1.99 ± 0.37 ng/mg of DNA respectively), decellularization time (SDS, SDC, CHAPS, Tw-20, and TX-100 had taken 28h, 35h, 51h, 48h, and 35 h respectively ), tensile strength (SDS, SDC, CHAPS, Tw-20, and TX-100 had Young’s Modulus of 5.8 MPa, 5.6 MPa, 3.2 MPa, 6.01 MPa respectively), and overall physical properties. The caprine pancreas was decellularized and found suitable for use as a scaffold after the decellularization mode and detergents were verified. This was done using a thorough series of analytical methods, including histological inspection, biochemical tests, and scanning electron microscopy (SEM). The scaffold's mechanical properties and degradation kinetics were meticulously analyzed to ensure their stability and long-term functionality. The biological performance of this scaffold was assessed through in-vitro cell culture studies, elucidating its ability to support cell adhesion, proliferation, and differentiation just like native tissue. After the scaffold underwent successful evaluations, a decellularized ECM was created for Hydrogel. Its physical and biological compatibility were then assessed. The structural integrity, composition, and biocompatibility of hydrogel were rigorously evaluated to ascertain its suitability as a scaffold material. Additionally, in-vivo studies for the full-thickness wound model were conducted to investigate the regenerative potential of this hydrogel in the Wistar rat model. The hydrogel was able to heal the wound without scar formation due to its wet wound healing potential. We also demonstrated that the scaffold enabled the pancreatic cells to grow in a naturally occurring pattern resembling a grape bunch; however, the hydrogel lost its growth factors attached to the ECM due to frequent grinding and sterilization, consequently, pancreatic cells were sporadically multiplying within the hydrogel. Conclusively, the results obtained in the research showcase that this novel scaffold serve as a viable replacement of the porcine derived organ (which run the risk of developing zoonotic disease upon xenotransplantation). Overall, the findings of this thesis highlight the potential of this novel reservoir, i.e., caprine pancreas, as a versatile biomaterial for tissue engineering application, offering a promising avenue for developing innovative therapeutic strategies to address various clinical challenges in tissue repair and regeneration
Sums of S-units and Perfect Powers in Recurrence Sequences
No full textDiophantine equations are polynomial or exponential equations in two or more variables for which integer solutions are sought. These equations look very simple but some are very difficult to solve. The same is the situation for recurrence relations. The recurrence relations sometimes arise in connection with combinatorial problems and sometimes arise in connection with the solutions of certain Diophantine equations. The best examples are Pell equations which are mostly solvable and the solutions constitute one or more classes of recurrence sequences. An interesting problem in connection with recurrence sequences is to find the terms which are perfect powers and a lot of work is available in the literature to identify such terms for almost all well-known sequences. A generalization of this problem is the study of Diophantine equations involving terms from some recurrence sequences. So far as the balancing sequence is concerned, the perfect powers occur rarely in the sums, differences of squares and sums or differences of cubes of two balancing numbers. However, in the case of general binary recurrence sequences, with some restrictions, only in finitely many cases, the sum of two terms is a perfect power. Given a finite set of primes S, an S-unit is an integer generated by the elements of S. An interesting problem is the study the Diophantine equation obtained by equating a linear combination of terms of a recurrence sequence with the sum of S-units. Under certain conditions, such Diophantine equations can be seen to admit a finite number of solutions. This can be achieved by providing an effective bound to the largest solution. The general Pell equation is the most common Diophantine equation that arises in connection with a variety of problems. A problem related to recurrence sequences and general Pell equations consists of searching for sums of two terms of some recurrence sequences in the solution sets of generalized Pell equations. With some conditions, the finiteness of such occurrences can be established by providing an upper bound for the number of solutions