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Essays on Economics of Green Sustainability and Environmental Quality - Insight from Developing Economies
No full textAnthropogenic activities have intensely converted the earth's ecosystem and resulted in major environmental changes over the last century or so. The widespread interference of human activities has resulted in major issues such as environmental pollution, land degradation, global warming/climate change, a scarcity of potable water supply, and biodiversity loss. Possible green solutions, such as the use of renewable energy and efficient technology, are gaining importance in order to lessen or remediate the harmful effects of anthropogenic activities, ensuring environmental sustainability. This study focuses on the four essays on energy and environmental economics in developing countries. The first essay examines the relationship between renewable, non-renewable energy, natural resources, human capital, and globalization on ecological footprint from 1990-2016 for developing countries. This study applies both static and dynamic econometrics approach to analyze the results. The findings revealed that economic growth, non renewable energy, natural resources, and urbanization are inducing the ecological footprint of developing countries and reducing the environment's quality. To cope up with this situation, developing countries are bound to use more fossil fuel energy. The second essay examines the dynamic impact of urbanization, economic structure, technological innovation, and population density on developing countries' ecological footprint and air quality (PM2.5) from 1990 to 2017. The study uses other variables like population density, energy consumption, and life expectancy to find out the long-run relationship among variables. We apply Westerlund co-integration, Mean Group (MG) and Pooled Mean Group (PMG) technique to ascertain the variables' long run and short run associations. The results reveal that, economic growth increases ecological footprint in these in long run. Similarly, the coefficient of industrialization is positive and significantly related to ecological footprint. However, the service sector negatively affects the ecological footprint in developing countries. Population density, urbanization, energy consumption, and life expectancy positively affect ecological footprint. Further, in the case of PM2.5, the results suggest that economic growth and industrial sectors have higher magnitude effects on the PM2.5 than the other variables. The service sector reduces PM2.5, whereas the coefficient value is not significant, but the agriculture sector positively influences PM2.5. Similarly, population density and urbanization contribution to PM2.5 are positive and significant. Hence, these countries should focus more on the investment in the renewable energy sector and make stringent environmental policy for protecting the nations from environmental issues. The third essay examines the role of corruption, green energy, trade, innovation, natural resources, and ICT on carbon dioxide (CO2) emissions in developing countries from 2000 to 2018 in developing economies. This study applies static econometrics technique like OLS, fixed effect and random effect model. However, for the analysis of main results SGMM is applied. It finds that the increase in corruption in developing countries adversely affects the environment, increasing CO2 emissions. Similarly, the interaction effect between corruption and natural resources increases CO2 emissions. On the other hand, corruption and green energy jointly decrease environmental quality. It finds that green energy and innovation can help lower carbon emissions. Furthermore, the interaction between corruption with innovation and information and communication technology (ICT) increases environmental quality in the long run. The findings also support the presence of the EKC hypothesis over the sample period. The findings imply that developing countries should raise their investment in green energy generation and stimulate green innovation in high-energy-intensive sectors to meet the Sustainable Development Goals (SDGs). Lastly, the fourth essay examines the nexus between financial development and the composite environmental quality index (CEQI); this also determines the interaction between financial development and other variables like economic growth, trade openness and renewable energy consumption. PSTR is used to determine the long run results by taking financial development as a threshold variable. This technique also solves the problem of endogeneity issue in the model. The results reveal a positive and statistically significant relationship between financial development and environmental quality in the lower regime of financial development. At the same time, it helps to reduce environmental pollution in the upper regime. Similarly, in the lower regime trade openness, FDI and population increase environmental pollution in developing countries. However, it reduces environmental pollution in the higher regime. When a country matures, the government considers environmental protection and allocates funds to build efficient technology to produce more products in the same amount of time. It may result in the country becoming self-sufficient in the production sector, which may reduce environmental pollution. However, in the lower regime, renewable energy reduces environmental pollution in the sampled countries
A Micro & Macro Study of Infrastructure Development: Evidence from BRICS Countries
No full textInfrastructure is vital for economic growth and overall sustainability of the nation. Infrastructure development reduces poverty, enhances regional competitiveness and creates employment. Nation’s competitive advantage can be achieved by optimal infrastructure investment and development. Monitoring of infrastructure development is critical for inclusive development of the nation. Infrastructure can be divided into energy, water, transportation and telecommunication infrastructure. Education and health infrastructure are also major sub categories of infrastructure. There is a requirement of infrastructure development in developing countries.
Developed countries focus more on maintenance of existing infrastructure structures. Optimal infrastructure investment is a key for quality directed and advantageous infrastructure development. In developing countries, the government is a key player in initiating and maintaining infrastructure development. Therefore, the major chuck of financing should come from government. Private players should be attracted to invest more in infrastructure sector through lucrative risk-return schemes.
The motivation of the study is basically to explore and examine infrastructure and related areas in a comprehensive manner. Infrastructure is under provided in many nations. There is a big gap between demand and supply of infrastructure. Infrastructure is also over provided in many countries and there is a requirement of optimal provision of infrastructure. Nations’ growth is positively impacted by infrastructure development. Thus, the study will attempt to depict importance and relevance of infrastructure. The study will provide solution to research problems concerning infrastructure taking India and other BRICS nations. BRICS nations have
comparable economic and social condition. BRICS have comparable per-capita income. BRICS are developing nations and exhibit similar infrastructure development scenario.
Infrastructure financing, infrastructure investment and development of infrastructure form the foundation of the study as there are limited studies covering these mentioned domains. The impact of infrastructure at macro level and micro level is relatively explored but robustness and consistency of results are questionable. Thus the impact of infrastructure at macro and micro level also forms the vital part of study’s research questions. At micro level the study links leverage with infrastructure firms’ investment in India and also links foreign investment with infrastructure firms’ performance in the Indian context.
The study investigates infrastructure and ecosystem relating to infrastructure. The impact of infrastructure investment and development are examined at macro and micro level. The study develops four objectives to find solution to research questions with the application of time series regression analysis, panel data regression analysis and infrastructure index construction methodology.
The study applies quantitative data collection and data analysis methods. These mentioned methods come under empirical research methods. The research questions forms the foundation of study’s four broad objectives. The study considers water, energy, transportation and telecommunication infrastructure for investigation. The data for infrastructure firms in India are collected from Prowess database. The macro economic variables data set representing BRICS nations are collected from Worldbank data base. The data set is analyzed with Eviews and Stata software.
The first objective examines the impact of leverage on firms’ investment. The research question for the first objective is; what is the status of performance of infrastructure firms in India? What is the effect of leverage on infrastructure firms’ investment in India? The study also explores some of the vital theories relating to this objective. These theories are agency theory, trade off theory and pecking order theory. This objective considers India for examination. The sample includes 379 infrastructure companies and time period varies from 2011 to 2017. Panel data
analysis is applied for examination. The techniques applied under panel data analysis are fixed effect, random effect and ordinary least square techniques. The study detects that leverage has an insignificant impact on the infrastructure firms’ investment.
The second objective investigates the impact of foreign investment on firm’s performance. The research question for second objective is; what is the impact of foreign investment on infrastructure firms’ performance in India? This objective considers India for investigation. Some of the foreign investment theories are the base for this objective. These theories are perfect competition theory of FDI and imperfect market theories of FDI. Imperfect market theories include monopolistic power theory, industrial organization approach, strength of currency, international trade, oligopolistic theory, internalization theory and discriminating paradigm to FDI. The sample includes 329 infrastructure companies and time period considered from 2011-2019. Panel data analysis is applied for examination and estimation. The
techniques applied under panel data analysis are GMM, fixed effect, random effect and ordinary least square techniques. The findings suggest that increase in foreign investment significantly impacts the infrastructure firms’ performance. These significant impacts are generally positive in many cases. In few cases these significant impacts are negative.
The third objective examines the impact of infrastructure on economic growth. This impact is examined taking individual nation within BRICS separately and by taking all nations of BRICS together. The research question for third objective is; what is the status of infrastructure development and advancement in India and other BRICS nations? What is the effect of infrastructure on economic growth in India and other BRICS nations? Few of the vital theories on economic growth are Romer theory, Schumpeter theory, Lewis theory and Rostow theory. Munnel (1992) and Aschauer (1989) execute critical researches on relationship between infrastructure and economic growth. This objective considers BRICS nations for examination. The time period comprises from 1980 to 2017. The study applies both time series analysis and
panel data analysis for examination. The findings of time series analysis suggest that the relationship between infrastructure and economic growth is insignificant for South Africa and Brazil. Transportation and energy infrastructure positively impacts economic growth for Russia. Telecommunication infrastructure negatively impacts economic growth for India. Transportation infrastructure negatively impacts economic growth for China. The findings of panel data analysis suggests that telecommunication infrastructure negatively impacts economic growth whereas energy infrastructure positively impacts economic growth.
The fourth objective constructs infrastructure index and infrastructure sub-indices. This part also examines the impact of infrastructure index on economic growth taking ordinary least square method (time series analysis). The infrastructure index is formulated by considering water, energy, transportation and telecommunication infrastructure. The validation of results also involves few necessary tests like jarque-bera test of normality, breusch-pagan-godfrey heteroscedasticity test, correlation test and breusch-godfrey serial correlation LM test. The research question for the fourth objective is; what is the process of infrastructure index and
infrastructure sub-indices formulation? What is the impact of formulated infrastructure index on economic growth? The prominent researches by Donaubauer et al. (2016) and McNeil et al.(2010) focus on construction of infrastructure index. The sample includes BRICS countries and time period ranges from 1984-2016.Transportation and telecommunication index depict increasing trend of growth from 1984 to 2016. Water index shows a decreasing trend from 1984-1991. Water index also shows increasing trend for rest of the time period 1992-2016. Energy index depicts increasing trend from 1984 to 1991. Energy index also shows decreasing trend from 1992-1999 followed by increasing trend for rest of the time frame 2000-2016. The final infrastructure index depicts increasing trend from 1984-2016. The study finds that the impact of infrastructure index on economic growth is insignificant.
Theoretical implications
The study contributes to studies concerning infrastructure, economic growth, infrastructure index, leverage, performance and foreign investment. The variables representing above mentioned heads differ according to study’s objective. The variations in relationship between variables are understood and interpreted by the study. Infrastructure generally positively impacts economic growth but the study also observes contradictory results. The study formulates infrastructure index to monitor progress to infrastructure in BRICS nations. There is an insignificant relationship between infrastructure index and economic growth. The impact of leverage on firm’s investment and impact of foreign investment on firm’s performance are also examined. Leverage has an insignificant impact on firm’s investment. Foreign investment has a significant impact on firm’s performance. There is a requirement of optimal infrastructure investment and development to positively impact economic growth. Infrastructure index varying over time period should positively impact economic growth. Foreign investment should positively impact infrastructure firms’ performance. Leverage should be optimally taken so that the impact of infrastructure firms’ investment is not negative.
Practical implications
The study’s findings are helpful to both managers and government as the study provides insight to them regarding infrastructure development scenario in developed nations and developing nations. The study especially focuses on India and BRICS nations. According to the study’s findings, managers need to be careful in choosing level of leverage for infrastructure firms in India. The managers also need to be cautious about choosing the level of foreign investment for infrastructure firms in India. Government should focus on optimal level of infrastructure investment in sub sectors of infrastructure. Government should avoid over and under infrastructure investment. The government should track progress of development and impact of infrastructure on economic growth by using the infrastructure index.
Value/ Originality
The study is novel as it examines impact of infrastructure both at macro and micro level taking time series analysis, panel data analysis and infrastructure index formulation. The study is unique as it considers India and BRICS nations for analysis. The impact of leverage on infrastructure firms’ investment and impact of foreign investment on infrastructure firms’ performance in India makes the study comprehensive
Dielectric, Magnetic, Magnetodielectric, and Magnetoimpedance Properties of Aurivillius Based Composites
No full textThe exciting electromagnetic phenomena are realized in the material when the charge and spin of the electrons are simultaneously coupled with each other. In this regard, the magnetodielectric (MD) coupling is one such mechanism, which can be achieved by systematically studying the dielectric constant under the external magnetic field. These MD materials have taken the significant attention of researchers due to the large coupling value, which could be used in magnetoelectric (ME) devices such as spintronic devices, tunable filters, ME sensors, and spin-charge transducers. Till now, various mechanisms have been developed to find out the MD coupling in the material and understand the origin of the MD effect; both the intrinsic and extrinsic have been proposed. The intrinsic MD coupling can yield a faster switching mechanism and low device loss than the extrinsic. The intrinsic MD coupling also provides the signature of the ME coupling in the material. Usually, the seldom existence of the magnetic and electric phases and the low operating temperature of the single-phase material provide the low value of the MD coupling and hinder its room temperature (RT) applications. Therefore, various types of composite fabrication may be an alternative avenue that yields large MD coupling and high operational temperature. In this regard, the Bi5Ti3FeO15 (BTFO) is a promising candidate with an orthorhombic crystal structure belonging to the Aurivillius family. BTFO material has attracted the attention of researchers due to its piezoelectric and ferroelectric (high curie temperature ~ 730 °C) characteristics. The bulk form of BTFO shows weak magnetic and MD coupling at RT. Hence, composite fabrication may be a potential path to enhance the magnetic and MD effect. For this purpose, the magnetic-rich La0.67Sr0.33MnO3 (LSMO) and Bi2Fe4O9 (BFO) compounds are selected for the composite fabrication. Finally, the present thesis systematically focuses on the magnetic, MD, and magnetoimpedance (MI) characteristics of the parent BTFO and its composite system.
For the comparison study, the polycrystalline BTFO sample is prepared via the solid-state (BTFOSS) and sol-gel (BTFO) process. Both the sample's dielectric, magnetic, and MD characteristics are studied systematically. The XRD and Raman analysis confirm the crystalline phase formation of the samples. The BTFOSS sample exhibits a high loss value (~ 25 times more) compared to the BTFO sample. The frequency-dependent dielectric constant reveals that the extrinsic source (space charge) is prominent in the BTFOSS sample with a temperature rise from 50 K to 300 K than in the BTFO sample. The existence of the MD coupling is also ascertained from the frequency and field-dependent MD effect. The maximum value of the ML% for the BTFOSS and BTFO samples is estimated to be ~ -4.71% and ~ -0.16% at 200 K, respectively. It reveals that a nearly 30 times loss reduction is observed in the BTFO sample than in the BTFOSS. However, the extrinsic sources (space charge polarization and resistive) are dominant in BTFOSS’s MD effect compared to the BTFO sample.
Thereafter, composites (1-x) BTFO-(x) LSMO (x = 0.1, 0.2, 0.3, and 0.4) are synthesized via sol-gel modified route, and phases are verified using XRD analysis. The SEM and TEM result conveys the distinct morphology of the two phases that demonstrated the plate-like grains and quasi-spherical particles of BTFO and LSMO phases. The magnetic studies reveal that the saturation magnetization (Ms ~7.0 emu/g) and coercive field (Hc ~1660 Oe) increased by nearly three and 66 times for 40% LSMO contained composite. The switching field distribution (SFD) plot indicates that strong exchange coupling exists in the x = 0.4 composite compared to others. The field-dependent MD studies reveal that maximum MD strength (~0.34%) and minimum magnetodielectric loss (ML) (~0.02%) are observed in x = 0.2 and 0.1 composites at 100 kHz, respectively. Additionally, the maximum MD coupling strength (-16.87 (emu/g)2) is observed in the x = 0.2 composite. The frequency-dependent magnetoresistance measurement determines the dominant capacitive MD effect in the composites.
The composites (1-x) Bi5Ti3FeO15-(x) Bi2Fe4O9 (x = 0.1, 0.2, 0.3, and 0.4) samples are prepared by the sol-gel-modified method, and the Rietveld refinement verifies the diphasic nature of the composites. The Raman spectra demonstrate the shifting of the vibrational modes due to adding the BFO phase, which is associated with the BO6 (B = Fe/Ti) octahedral. Magnetization data reveals the highest value of and is found for 20% composite, which is caused by the interaction among the AFM/FM magnetic ordering. Field variation of MD data shows ~30 times enhancement of MD% and ~7 times reduction of the ML% for x = 0.2 sample as compared to the pure sample. The field-dependent capacitive MI and Cole-Cole plot analysis reveals the capacitive origin behind the MD effect.
Finally, composite (1-x) BTFO-(x)[(0.2) LSMO-(0.3) BFO] (x = 0.5) is successfully prepared using the sol-gel modified technique. The XRD study confirmed the existence of triple (A21am, R-3c, and Pbam) phases in the composite sample. The SEM analysis has confirmed the presence of homogeneous and heterogeneous microstructures of pure and composite samples. Adding the magnetic LSMO and BFO phases enhance the overall magnetic properties of the composite sample. The magnetic parameters Ms and Hc in the composite are enhanced by nearly three times than the parent BTFO. It is due to the inherent d-d exchange interaction between the Fe-Fe, Fe-Mn, and Mn-Mn ions. The field-induced maximum strength of the MD effect is about ~ 0.12% at 50 kHz observed in the composite sample. This MD effect can be the combined effect of strain magnetostrictive LSMO and the inverse Dzyaloshinskii-Moriya interaction generated by the non-collinear Fe ions in the AFM BFO phase. The magnetic field-dependent Cole-Cole plot and field variation of MI plot analysis also reveals the resistive origin behind the MD effect in the composite.
Hence, the MD effect in the Aurivillius BTFO compound is explored, and the strength of the magnetic and MD effect is improved via the addition of magnetic-rich compounds. The above characteristics of the BTFO and its composite system might be applicable to multifunctional devices
Acoustic Attenuation of Periodic Helmholtz Resonator and Their Use in Designing Periodic Scatterers for Outdoor Noise Control
No full textPresent thesis deals with the study of various configurations of Helmholtz resonators, combined with various acoustic elements such as perforated plates, micro perforated plates and porous materials. It also emphasizes the noise control and metamaterials perspective including designing periodic scatterer made with array of Helmholtz resonators along its length for outdoor noise control in low frequency regime. The research starts with studying a Helmholtz resonator from acoustic metamaterial perspective. Helmholtz resonator is a single negative metamaterial where the effective bulk modulus is negative. The said fact has been re-established analytically and verified by results obtained from simulations. First the scattering parameters have been calculated from transfer matrix which have been used to calculate the effective acoustic properties with an assumption that the material under investigation is homogeneous, and width of the sample is much smaller compared to the wavelength corresponding to maximum frequency of interest. Additionally, the experimental results are presented which support the said observations. Next, various configurations of Helmholtz resonators have been studied to attain double negative effective properties. The various configurations are Helmholtz resonators in series, parallel, and the dual Helmholtz resonators in series and parallel. The said configurations are also studied with the similar and dissimilar resonators. Out of seven configurations, it has been shown that with five configurations attain double negative properties. Additionally, with an array of Helmholtz resonators, it has been demonstrated that the effective bulk modulus and the effective density are getting negative at resonance frequency regime having elevated frequency bandwidth. Following, the acoustic elements such as perforated plate (PP) and micro perforated plate (MPP) have been combined with Helmholtz resonator and have been studied to attain double negative effective properties in broadband. Total eight different configurations have been conceptualized and corresponding analytical solutions supported with experimental measurements have been presented. Afterwards, with an intention to broaden the bandwidth of negative effective properties, the porous material has been installed in Helmholtz resonator cavity and have been studied. On installing the porous material inside the resonator, the peak amplitude of transmission loss around resonance frequency regime is getting dampened and widened. The detailed study discovers that the resonator filled completely with porous material is practically not of interest because of its very low amplitude. However, with array configurations it has been shown that the resonance peak amplitude is getting significantly elevated in broadband which can address many practical problems. From metamaterial perspective, it also has been demonstrated that on installing porous material in resonator cavity, the hybrid Helmholtz resonator is turning into a double negative metamaterial which is also observed with finite array of Helmholtz resonators. Eventually, the noise of outdoor unit of the split type air conditioners (AC) have been studied. The experimental measurements show that the noise of outdoor unit carries dominant low frequency components with high amplitude typically below 200 Hz. The tuneable periodic scatterer has been suggested as a noise barrier where each scatterer is an array of Helmholtz resonators along its length. A detailed design and laboratory level characterization agreeing the results obtained from simulations have been presented. After deployment of said designed noise barrier in front of three outdoor units of split type air-conditioners, the overall noise reduction have been presented
Biotherapeutic Amelioration of Enteric Infection and Colon Cancer using Specific Probiotics and Prebiotics
No full textEnteric diseases such as colon cancer and enteric infections are a major threat to the society. Colon cancer accounts for the fourth most common cause of death and the third most common cancer affecting the people worldwide. In the present research, probiotic strains have been isolated from human gut and screened for its biosafety aspects and probiotic characteristics to prevent enteric infection by Salmonella enterica subsp. enterica serovar Typhimurium. The efficacy of the screened strains was determined by using simulated colonic model fermenting insoluble and non-digestible fibres from the food grains after oro-gastrointestinal digestion. The isolated strains could produce multiple bacteriocins, vitamins like folates and riboflavin and short chain fatty acids. Their efficacy was also tested in Drosophila model infected with Salmonella Typhimurium and was found to be effective in both prophylactic and therapeutic mode of treatment with the isolated probiotic strains. The probiotic strains enhanced the survival of adult Drosophila under oxidative stress and improved the total antioxidant status of the fly. The isolated probiotic strains thus showed prospectus to be used as live biotherapeutic product for the prevention and treatment of enteric infection by Salmonella Typhimurium. A prebiotic based drug delivery system was developed by conjugating ferulic acid (FA) to fructo-oligosaccharide (FOS) increasing the bioavailability of FA in the intestine. Two types of\ conjugates were synthesized: FA FOS I water insoluble self-assembled microparticles and FA FOS II water soluble conjugate. Both showed anti-cancer activity, cell cycle arrest and apoptosis in-vitro with high selectivity towards cancer cells. The FA FOS II acted as a pro drug which carried FA to the intestine and released them by the action of microbiota. This phenomenon increased the bioavailability of FA in the large intestine and increased the t1/2 of FA in the rat plasma from 30 min to 240 min, which suggests that the free FA is slowly and persistently released by the microbial action in the large intestine enabling controlled and sustained release of the payload (FA) at the target site (colon) and persistence in the plasma. The anticancer efficacy of FA FOS conjugates was tested in both xenograft mice model of colon cancer and in colitis induced colon cancer mice model. There was improvement in the antioxidant profile in the mice plasma and reduction in the inflammation of the intestine treated with FA FOS II evident from immunohistochemistry (IHC) profile of the mouse colon tissue. The FA FOS conjugate also positively modulated the gut microbiota by enhancing the beneficial population of bacteria Lachnospiraceae, Ruminococcaceae and reducing the potentially harmful population of the microbiota Bacteriodes and Prevotella. Both FA FOS I and FA FOS II increased the immune mediated tumour surveillance by enhancing the presence of helper T-cells and cytotoxic-T cells in the tumour microenvironment in the AOM DSS mediated colon cancer model
Loading Response of Laminated CFRP Composites with Hole cutout: Geometrical Design Effect on Material Strength and Failure Mechanism
No full textIn recent decades, CFRP laminates have become popular material among design engineers due to their high strength and stiffness-to-weight ratio, corrosion resistance, thermal stability and chemical inertness. It is being exploited in many engineering applications like automobile, aerospace, civil, marine, commodity, sports, etc. As a further matter, CFRP is typically a brittle material and catastrophically fails without sufficient warning. The catastrophic failure of CFRP is usually compensated by a conservative design limit which hinders exploiting outstanding materials’ mechanical properties. The design of the component must be compatible with the material and must be able to resist specific loading condition. Since welding of CFRP components are not possible therefore design of open hole in the component is inevitable; it is made to incorporate pins, rivets or bolts for assembly of the components into the final structure. Moreover, holes or cutouts in the component are also used to lighten the structure and fulfill some functional requirements such as the passage of electrical and fuel lines, accommodation of doors and windows. Thus, understanding material response due to the design of hole/cutout is of utmost importance. The present study demonstrates the effect of hole, hole shape, hole size and stacking sequence on laminated CFRP components under two different loading condition. Additionally, detailed failure mechanism and strength prediction models have also been assessed. The study started through experimental investigation on the effect of stacking sequence, hole size, and hole shape on the tensile strength of CFRP laminate. Reduction in Open Hole Tensile (OHT) strength is observed when stacking sequence is changed from [0]8 to [0/90]2s and when the hole size is increased. However, OHT strength is noticed to get increased when hole shape is changed from circular to square. Laminates containing square shaped hole demonstrate less sensitivity towards tensile strength and show negligible effect of stacking sequences on the normalized strength than the circular hole. A further testing program was performed on CFRP laminates under flexural loading. Flexural and Open Hole Flexural (OHF) test of CFRP as a function of stacking sequences report that the [0]8 laminates have the highest flexural and open hole flexural strength. During the evaluation of strength retention value, [02/902]s laminate is found to be best among all investigated stacking sequences. [02/902]s and [90/0]2s is found best for better isotropy of open hole flexural strength among the laminates having first ply at 0◦ and 90◦, respectively. Further, a comparative analysis has been done on CFRP laminate to understand the design aspect of holes/cutouts under the tensile and flexural loading. Tensile loading is found to be more detrimental than flexural loading for composite laminate with hole. SEM and optical micrographs have been analyzed to perceive the failure mechanisms of laminates under two different loading conditions. Mode I dominated delamination and mode II dominated delamination are found to be prevalent in OHT (open hole tensile) and OHF (open hole flexural) failure, respectively. The results of the testing program and strength prediction models were compared and assessed through deterministic analysis. Longitudinal laminates show some discrepancy between predicted data and experimental data. However, crossply laminates are found to approach congruence with experimental data. In deterministic analysis, the failure pattern of each laminate system has been studied. The microscopic examination of fractured samples has also been done to study failure mechanisms. Both longitudinal and crossply laminates show a brittle fracture, but the splitting in longitudinallaminates accorded a hint of gradual failure because laminates continue to bear load; Nevertheless, laminates suddenly lead to lateral brittle fracture
Understanding Variability of Indian Summer Monsoon Rainfall in Different Time Scales Using Global Coupled and Regional Models
No full textThe Indian Summer Monsoon (ISM) is a well-organised land-ocean-atmosphere coupled system known as the southwest monsoon. The southwest monsoon season (June-September) in the annual cycle is distinguished from the rest of the seasons in terms of onset, propagation/maintenance and retreat phases. The ISM exhibits significant spatial and temporal variability in monsoon circulation and associated rainfall. Accurate spatial and temporal rainfall information helps to understand the hydrological processes on a country scale. The shortage of observational networks or damage caused by geophysical extreme events limits the actual picture of rainfall characteristics and variability of ISM. The observational network is limited to providing insights into the possible reasons for the characteristic variability of that particular observation. In particular to ISM rainfall (ISMR) variability, the evolution of different ocean and atmospheric conditions in relation to the teleconnections is vital, and this information is not readily available from the observational network. However, satellite products have emerged, delivering data at a different spatiotemporal resolution. The availability of satellite precipitation products is expected to present realistic monsoon rainfall characteristics at different time scales. Further, the climate, seasonal, and regional models can provide numerous ocean-atmosphere variables at different time and spatial scales, which are alternatives to the observational network for understanding ISMR variability. However, these models have shown limited skill in predicting ISM rainfall and its variability. The representation of slowly evolving modes in the tropical ocean, as well as the accompanying ISMR variability, is a tough challenge for operational and research communities. The magnitude, location, and timing of ENSO occurrences influence the performance of the El Niño-Southern Oscillation (ENSO). Several Coupled General Circulation Models (CGCMS) studies mostly focused on the effects of developing El Niño and La Niña on summer rainfall over India. Recent studies have discovered that, like growing ENSO, the decaying stages of ENSO modulate the ISMR. The significance of ENSO decay phases in seasonal forecasting encouraged to study of the different responses of ISMR to distinct El Niño and La Niña decay phases. Previous studies suggested the seasonal mean ISMR forecasts rely on the skillful representation of interannual modes mainly ENSO, Indian Ocean Dipole (IOD) and co-occurrence of both in the tropical ocean and their associated teleconnection patterns. In order to ensure the consistency between large-scale driving fields and model solutions, spectral nudging has been used, particularly in the case of seasonal simulations. Therefore, the present thesis is aimed to demonstrate (i) the performance of global and seasonal models in capturing different phases of the El-Niño/LaNiña and IOD/ENSO and their effects on the simulation of ISMR and its variability across the temporal scales and (ii) the advantage of high-resolution in capturing regional features of ISMR and its variability. The thesis is structured accordingly, beginning from the introduction chapter to the concluding chapter along with four working chapters. The first working chapter investigates the reliability and accuracy of high-resolution satellite rainfall products such as TRMM, GPM, IMR, and HEM are compared against rain gauge observation of IMD. GPM has captured the all-India seasonal rainfall (6.8 mm day –1) close to the IMD rainfall (6.7 mm day –1). While the seasonal all-India rainfall is overestimated in TRMM (7.6 mm day –1), HEM (8.4 mm day –1), and IMR (14.2 mm day –1) products. The GPM has reasonably captured All-India rainfall at daily, monthly, and seasonal scales than the others. The second working chapter is focused on understanding the variations in the El Niño decay phases and their diverse impacts on ISM rainfall using IMD observation and CMIP6 model outputs. The El Niño/La Niña decays are classified into three categories based on their rapid and/or slow transition with respect to the following boreal summer season. When El Niño early-decay, El Niño mid-decay, and La Niña no-decay occurrences occur in the summer, widespread rainfall occurs throughout India; when El Niño early-decay, La Niña mid-decay, and La Niña no-decay occur, the rainfall is suppressed. The MMM of top ~ 20% of CMIP6 models could capture the ISM rainfall anomaly patterns in the summer of El Niño early-decay, La Niña early-decay and El Niño mid-decay; however, it failed in the other three phases (La Niña early-decay, La Niña mid-decay, and El Niño no-decay in summer) because of the unrealistic representation of IOD and TIO SST anomaly. It is noted that most of the models have a tendency to show strong IOD during ENSO decay summers, which may influence the large-scale circulation features and regional rainfall anomalies. The seasonal mean ISM rainfall forecasts directly depend on the representation of large-scale features associated with ENSO developing as well as the ENSO decaying phases and their associated responses. The third working chapter addresses the credibility of high resolution in capturing interannual modes such as ENSO, IOD and their co-occurrences in relation to ISM rainfall. For this purpose, the high-resolution (38 km grid-spacing) seasonal model (CFSv2) and coarser resolution (~100 km grid-spacing) ensemble means of North American MultiModel Ensemble (NMME) hindcasts are evaluated against IMD observations. The overall mean AISMR (standard deviation) in CFSv2 is 6.3 mm day-1 (0.42 mm day-1), which shows good agreement with an observational value of 6.9 mm day-1 (0.59 mm day-1). The standard deviation (0.25 mm day-1) is inadequately represented despite the close representation of MMM (6.1 mm day-1) with observation. Even when SST anomalies are positioned precisely, the ISM rainfall patterns show significant changes in spatial and temporal variability. Accurate SST patterns during the Pure El Niño (P-EN), Pure La Niña (P-LN), Pure Positive IOD (P-pIOD), Pure Negative IOD (P-nIOD), Co-occurrence of El Niño with positive IOD (Co_EN_pIOD), and Co-occurrence of La Niña with negative IOD (Co_LN_nIOD) must be captured for better representation of circulations needed for the better prediction of the different categories of extremes. The fourth working chapter examines the performance of spectral nudging in the dynamical downscaling of ISMR in the WRF model framework. Two experiments were conducted i) simulation using spectral nudging (SN), in which the zonal, meridional and temperature fields are nudged, and ii) simulation with no nudging (NSN). The spectral nudging accurately simulated ISMR characteristics at seasonal, sub-seasonal, and across homogenous regions. The area-averaged RMSE is less for SN in all the homogeneous regions compared to NSN. Significant improvements are seen in the first 60 days’ simulation of SN over India and its homogeneous regions. At the same time, the NSN experiment showed relatively poor performance. Thus, the study highlights the importance of spectral nudging to high-resolution downscaling for improved long-range simulations. All the conclusions are briefed in the summary and conclusion chapter. The overall outcomes of the present dissertation are (i) better satellite product capturing realistic ISM rainfall characteristics and variability, (ii) insights on the unrevealing processes associated with ENSO decay phases that influence the interannual variability of ISMR (iii) the necessity of high-resolution for improved ISM rainfall variability as studied from seasonal as well as mesoscale WRF model. These efforts are intended to help state-of-the-art dynamical models identify the systematic biases and their removal for realistic representations of ISM rainfall and variability
Abatement of 2-chlorophenol from the Aqueous Environment by Implementing the Adsorbents Prepared from Lignocellulosic Biomasses
No full textThe scarcity of clean and consumable water is a serious concern in the current era. Gradually diminishing water bodies are further getting contaminated by hazardous contaminants. 2-Chlorophenol (2-CP) is a hazardous pollutant capable of causing dreadful diseases. Despite toxicity 2-CP is widely used in several industries. The solubility of 2-CP in water is significantly higher i.e. 28 g L-1 at 20 oC. The United States environmental pollution agency has issued permissible levels for 2-CP in consumable water and effluents as high as 0.1 and 2 μg L-1. Most of the wastewater (polluted by 2-CP) treatment technologies have limitations in the form of operation cost, operation duration, and complicated technology. On the other hand, the adsorption method is an economical, versatile, and robust technique with the capability to effectively remove 2-CP from the aqueous environment. The present study aims to investigate the 2-CP adsorption potential of laboratoryprepared adsorbents neem seed activated carbon (NAC) and rice straw activated carbon (RSAC) from aqueous environments. Furthermore, commercially available powdered activated carbon (PAC) was used for 2-CP adsorption for performance comparison. The NAC and RSAC were prepared from their respective precursors via thermochemical activation routes. The yield of NAC and RSAC was found to be 80.49 and 78.17%, respectively. Characterization studies have revealed that all the adsorbents are composed of more than 55% carbon. The pHpzc values of NAC, RSAC, and PAC were 7.12, 7.5, and 9.12, respectively. The BET analysis has confirmed the presence of both mesopores and micropores. The BET surface areas were 248, 239, and 547 m2 g-1 for NAC, RSAC, and PAC, respectively. All three of the adsorbents were confirmed to be amorphous by XRD analysis. The FTIR analysis has revealed the presence of carbonyl, nitrile, hydroxyl, and silanol groups in abundance on the surface of all the adsorbents. The Raman spectroscopy analysis has provided evidence for the graphitic structural arrangement for NAC and RSAC, whereas the defective structural arrangement for PAC. The univariate optimization experimentations were performed to optimize process parameters. The optimal NAC, RSAC, and PAC doses were found to be 1.2, 1.25, and 0.72 g L-1. The optimal pH values and equilibrium contact times were found to be 8:120 min, 8: 125 min, and 9: 90 min for NAC, RSAC, and PAC, respectively, in the order of their appearance. The temperature increment has a negative impact on the adsorption capacity. The kinetics studies revealed that the 2-CP-NAC adsorption system followed pseudo-second-order kinetics. In contrast, both RSAC and PAC were found to be in good agreement with pseudo-firstorder kinetics. The adsorption kinetics studies have confirmed the existence of both film and pore diffusions for all three adsorbents. The experimental data for 2-CP adsorption for isotherm modeling was found to be fitted to Langmuir, Redlich-Peterson, and Freundlich models for NAC, RSAC, and PAC, respectively. From the Langmuir isotherm model, the maximum adsorption capacities for 2-CP by NAC, RSAC, and PAC were found to be 43.5, 45.34, and 54.87 mg g-1, respectively. Adsorption thermodynamics studies have revealed that the 2-CP adsorption was exothermic by nature. The negativity of Gibb's free energy values has suggested the spontaneity of the 2-CP adsorption onto the adsorbents. Statistical model for adsorption thermodynamics studies has satisfactorily explained the thermodynamic behavior at micromolecular levels and was also found to be in accordance with the outcomes of the classical model. The isosteric heat of adsorption estimation for 2-CP adsorption systems revealed that the surface of NAC and RSAC were energetically homogeneous, whereas the surface was energetically heterogeneous for PAC. Taguchi's experimental design was employed to statistically optimize the process parameters for 2-CP adsorption onto NAC and RSAC. The results have revealed that Taguchi's design has successfully optimized the process parameters with the help of S/N ratio estimation and analysis of variance. The most influential factors were the initial concentration of 2-CP and pH for NAC and RSAC, respectively. The continuous adsorption of 2-CP was investigated with an up-flow pattern fixed bed adsorption column. The column adsorption studies have revealed that the breakthrough time was reduced with an increment in 2-CP concentration and flow rate. The Thomas and Yoon-Nelson kinetics models were found to be fitted well with the experimental data. The reusability studies of the adsorbents were carried out by employing desorption techniques. Among the physical desorption techniques, the microwave irradiation-based desorption technique was the bestperforming desorption method rendering as high as 85.49% desorption efficiency for RSAC. Among the chemical-mediated desorption methods, the ethanol-mediated elution technique was the best, with the highest desorption percentage obtained at 93.45% for PAC. The investigation of the 2-CP adsorption mechanism onto three adsorbents was predominantly governed by ππ electron donor-acceptor complexation, hydrogen bonding, electrostatic interaction, etc., for 2-CP adsorption onto NAC, RSAC, and PAC, respectively
The Molecular Mechanism of Nanoparticle-Mediated Toxicity, Regeneration and Wound Healing in Drosophila Melanogaster
No full textThe development of nanoparticles (NPs) in nanotechnology has emerged as a potential target for studying applied science and technology. NPs are used in various sectors, such as food industries, cosmetics, biomedical, drug design, and drug delivery. NPs are classified as inorganic or organic, carbon or polymeric or ceramic-based, and metal or metal oxides. NPs showed both beneficial and harmful effects when exposed to an organism. Due to the worldwide applications of NPs, humans and animals are significantly exposed. The toxicity of NPs may depend on the nanomaterial's shape, size, and surface area. NPs showed cytotoxic and genotoxic and may alter the physiology and behaviour of the organism by altering various signaling pathways. Metal, metal oxide and polymeric NPs were used extensively in food packaging due to their antimicrobial and antifungal activities. However, when we consume these foods, these NPs can easily enter our body and causes many symptoms and disease. Many studies have reported the toxicity of NPs using various in vitro and in vivo models. But, the studies failed to underline the toxicity, safe, and appropriate applications of NPs simultaneously. Therefore, the current study aims to scrutinise the effect and molecular mechanism of NPs mediated toxicity and its application in regeneration and wound healing by using Drosophila melanogaster as a model organism. The first objective aims to investigate the effects of Al O nanoparticles (AlNPs) as potential mutagen and teratogen and their toxicity mechanism. AINPS were fed orally along with standard food and were found to alter Drosophila’s growth, development, and behavior. It was observed that both larvae and adult flies showed high ROS formation and neuronal disorder by altering the antioxidant enzymes. AINPs showed high toxicity to gut cells, resulting in DNA damage, micronuclei formation, and mitochondria depletion. The second objective elucidates the toxicity of polymeric Fe3O4-GG nanocomposite (GGNCS) and its application in nanomedicine. After feeding GGNCS, the toxicity profile was checked and found negligible cytotoxic effects according to their concentrations. GGNCS were able to reduce flyweight, glucose, and triglyceride contents. The behavioural abnormalities were also observed on treated larvae and files. Alteration of antioxidant enzymes in treatment showed ROS generation in a concentration-dependent manner. The third objective is to investigate the toxicity and role of platinum nanoparticles (PtNPs) for wound healing and regeneration application in nanomedicine. Investigation showed that PtNPs have a very negligible amount of cytotoxic effect. But, PtNPs can scavenge the ROS by mimicking an antioxidant enzyme and protecting the cells from oxidative stress. PtNPs also interact with hemolymph and help in angiogenesis. It was also observed that PtNPs help in mitochondrial biogenesis. Further, PtNPs were also applied in wound healing and observed that they fastened the wound healing and tissue regeneration process compared to the non-treatment. Together, all the studies revealed the toxic effect and the safe application of metal oxide (i.e., AlNPs), polymeric (i.e., GGNCs), and metal (i.e., PtNPs) NPs
Estimating Parameters of Certain Lifetime Statistical Models Using Censored Samples
No full textIn Chapter 1, we discuss the literature review on the related problems and give some motivation for studying the problem under consideration. Also, the summary of the results obtained in the thesis has been discussed there. In Chapter 2, we discuss some basic results from decision theoretic as well as classical points of view on estimation theory. In Chapter 3, the problem of estimating parameters of the generalized inverse Lindley (GIL) distribution using type-I hybrid and general progressive type-II censored samples has been considered. As the maximum likelihood estimators (MLEs) do not have closed-form expressions, they are obtained by numerically solving a system of nonlinear equations using certain approximation methods. The two approximate Bayes estimators using Tierney and Kadane’s method and Gibbs sampling method under general entropy and LINEX loss functions are derived. For deriving Bayes estimators gamma prior for the parameters is considered. Several confidence intervals are also proposed, such as the asymptotic confidence intervals (ACIs), bootstrap confidence intervals (Boot-p and Boot-t), and the highest posterior density (HPD) intervals. An extensive simulation study has been conducted to evaluate all the estimators’ performances numerically. The point estimators are compared through their biases and mean squared errors (MSEs). The performances of confidence intervals are evaluated using coverage probability (CP), average length (AL), and probability coverage density (PCD). Some real-life datasets have been considered for illustrative purposes. In Chapter 4, the problems of point and interval estimation for the associated parameters, along with the reliability function (r(x)) and the hazard rate function (h(x)) of the inverse Gompertz distribution, are considered using a unified hybrid censoring scheme. In the case of point estimation, some classical estimators, such as the MLE and the maximum product spacing estimator (MPSE), are derived. Further, Bayes estimators are obtained with respect to a suitable prior for the associated parameters under the balanced loss functions (balanced LINEX loss function and balanced general entropy loss function). The ACIs using the MLEs and MPSEs of the parameters are derived as the interval estimators. Further, the equal tailed and the HPD intervals are derived using the posterior samples. The MSEs are used to compare the point estimators, whereas the interval estimators are compared through their CP and ALs. A real dataset is considered for application purposes. In Chapter 5, the problems of point and interval estimation of the parameters of the inverse Gaussian distribution is considered using the sample observed in the presence of a unified type-II progressive hybrid censoring scheme with binomial removals. In the case of point estimation, the MLEs are derived using Newton’s method, whereas the Bayes estimators are derived using Tierney-Kadane’s approximation and Gibbs sampling procedure. The Bayes estimators are derived assuming that the parameters follow two independent gamma priors, where the loss function is taken as the general entropy loss function. Further, the ACIs, Boot-p confidence intervals, Boot-t confidence intervals, and HPD intervals are constructed as the interval estimators. An extensive simulation study has been carried out to compare the performances of all the point and interval estimators using the Monte Carlo simulation procedure. The point estimators are compared in terms of their biases and MSEs, whereas the interval estimators are compared by their CPs and ALs. Moreover, the one- and two sample Bayesian prediction procedure has been utilized to predict censored units from the real data under the considered censoring scheme and also to predict the order statistics from a future sample. A real-life example is considered for illustration purposes. In Chapter 6, the problem of estimating scale parameters and their reciprocals (known as hazard rates) from two exponential populations with ordered scale parameters has been considered under the progressive type-II censoring scheme. The MLEs and the uniformly minimum variance unbiased estimators (UMVUEs) are derived. Sufficient conditions are derived for improving the estimators in certain classes using a decision-theoretic approach. Consequently, some improved estimators over the MLEs and the UMVUEs are derived. A numerical comparison among all the proposed estimators is made, and conclusions are drawn regarding their performances with respect to the certain bowl-shaped loss function. In Chapter 7, the problems of point and interval estimation for the parameters of two gamma populations with common shape or rate parameter have been considered in the presence of the progressive type-II censoring scheme. The MLEs and MPSEs are derived for the common shape/rate parameter and the other two nuisance parameters after numerically solving a system of non-linear equations. The ACIs using the MLEs and MPSEs are derived for the associated model parameters. Moreover, the approximate Bayes estimators are derived using the Markov chain Monte Carlo (MCMC) procedure, known as the Gibbs sampling. Further, the HPD intervals for the model parameters are also derived using the posterior samples obtained from the Gibbs sampling. An extensive simulation study has been carried out to compare all the proposed estimators numerically. Some real datasets have been considered to demonstrate the potential application of our model problem