2. Thesis and Dissertations

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    Assessing the Impact of Climate Change on Agriculture: Empirical Evidence from a South Indian State
    (National Institute of Technology Karnataka, Surathkal, 2019) Kalli, Rajesh M.; Jena, Pradyot Ranjan
    The present study provides a detailed empirical analysis of climate change impact on agriculture in Karnataka. Erratic rainfall and steady rise in temperature in tropical arid and semi-arid region has a significant impact on the farming communities. Against this backdrop, the present study has used a climate dataset constructed at finer spatial level to analyze the climate change impact on the net revenue and crop yields. A panel data, with a cross section of 20 districts and a time period of 21 years (1992 – 2012) was considered in the study. The fixed effect regression results show that temperature has a significant negative effect on the net revenue and crop yields. However, rainfall had a significant positive impact on net revenue and yields. Further, the study has also probed to analyze the agricultural vulnerability to climate change using indicator based method. The results showed that entire seven districts from north interior region were categorized in the extremely and highly vulnerable region. Out of eleven districts in south interior region, three were categorized in the extremely and highly vulnerable region. However, the result broadly indicated that agriculture in the north interior region of Karnataka is highly susceptible to climate change.
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    Design and Control of LowVoltage Dynamic Voltage Restorers employing Semi-Z-Source Inverters
    (National Institute of Technology Karnataka, Surathkal, 2019) Remya, V. K.; Parthiban, P.
    Industries have attained tremendous growth rate in recent years with the advent of computers, sensitive equipment and control systems. Most of the processes involving these devices are disturbed and sometimes damaged by the voltage quality problems. Dynamic Voltage Restorer (DVR) is a power electronic converter based device that protects the sensitive loads from experiencing the power quality problems. The main objective of the research work is to find an alternative to the commonly used Full-Bridge (FB) inverter in the DVR structure. The research work here presents two novel topologies of constant dc-link type DVR based on a) semi-Z-source inverter and b) differential semiZ-source inverter. The semi-Z-source inverter offers the same output voltage range as the FB inverter with reduced number of switches. The differential semi-Z-source inverter gives double the output voltage range with four semi-conductor switches compared to the FB inverter. The Modified Sinusoidal Pulse Width Modulation Technique (MSPWM) is used for generating the switching pulses for the semi-Z-source inverter and differential semi-Z-source inverter. The two DVR topologies proposed effectively mitigate the voltage sag by employing feed-forward control and modified feed-back control. The numerical simulations of the proposed DVR topologies for different voltage disturbances are carried out in MATLAB/ Simulink environment. The application of semi-Z-source inverter and differential semi-Z-source inverter as DVR inverter is validated by the results obtained from the laboratory prototype. The MSPWM for the independent inverter operation, rms voltage method for voltage sag detection and DVR inverter control are implemented in Xilinx-Basys-3 FPGA. The voltage sag generation is implemented using Solid State Relays, transformers and PIC microcontroller. The experimental results of voltage sag compensation by proposed DVR approves the application of semi-Z-source inverter as DVR inverter.
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    Women’s Writing in Kannada: An Analysis of Select Writings of Sarah Aboobackar
    (National Institute of Technology Karnataka, Surathkal, 2016) Kamath, Ambika; Koudur, Shashikantha
    The aim of this study is to analyse one of the finest women writers of the Kannada literary world – Sarah Aboobackar. She belongs to the Beary community, a Muslim ethnic minority community, identified with the coastal regions of Karnataka and northern parts of Kerala. Sarah emerged on the Kannada literary scene in the 1980s. She is a gifted writer and has won much acclaim. Sarah is recognized as one of the major literary figures of the Bandaya period (Navyothara or post-modern in Kannada) and is considered one of the powerful voices in contemporary Kannada literature. She is important to the Kannada literary scene because she is the first Muslim writer to emerge in Kannada. The new vigour and energy that she brought into the Kannada context got her wide acclaim and she has been adorned with some of the very prestigious awards. Sarah’s writings are a door opened into the lives of people not only of Beary community, but that of coastal Karnataka. When she focuses on Beary community, she portrays the problems caused by practices like dowry, polygamy and instant divorce (talaq). Though the community lives in close proximity, many of the problems faced by the community were not known to the wider public. Sarah’s portrayal of her society gives a rare insight into the culture of an ethnic group, thereby providing an exceptional glimpse of the lived-in realities of a people living amidst us, more the reason to take up her writings for analysis. At a time when community relations are under duress in the Indian context, it becomes an issue of equivalent importance that Sarah be read and contextualised. The current research has research method inputs from Textual Analysis, Autobiography, Ethnographic Method, Quantitative Method, and Interviewing. Therefore, this research is a mix of qualitative and quantitative studies. The study merges both descriptive and exploratory approaches in order to provide a better understanding of literature and culture of the people of a region. Since the study is about the writings of a woman from an ethnic community, and since Sarah is an important female voice from Kannada literature, who is assertive on questions ofgender and identity, it becomes appropriate to consider the questions of feminist critical theory, and gender studies, apart from questions of Comparative Literature. Sarah's belongingness and indebtedness to the Kannada tradition is discussed. For a brief comparative study of Sarah Aboobackar, significant Muslim women writers like Qurratulain Hyder, Ismat Chugtai and Banu Musthaq, are selected who are known to be the outstanding voices emerging from the margins. In addition, since the researcher is working on Sarah Aboobackar from Kannada literature, it becomes essential to look at Translation studies and its relevance to Comparative studies. The qualitative part of the study attempts to analyze the writings of Sarah, apart from trying to understand the lived-in realities and culture of Beary community, represented through the literature of a region. It is believed that a text speaks of the lived-in experiences of the author and gives us a picture of his or her world. We look into her autobiographical writings and identify her distinction between the religious text and the interpretation of that text; we look at her fictional writings and look for patterns of representation and identify Sarah's contribution in crafting out a New Womanhood in her fiction. The quantitative study is exploratory in nature and is more limited than the qualitative part. The data collected using sections of Sarah’s readership is analyzed and interpreted, and the results obtained, not very surprisingly, shows that girls agree more with Sarah as a writer than boys do. This descriptive and exploratory research, it is expected, will throw up new questions in future, with a possibility of opening up new research areas.
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    Studies on Performance Characteristics of Hydrogen Loaded Concrete Mixes
    (National Institute of Technology Karnataka, Surathkal, 2016) Malkapur, Santhosh M.; Narasimhan, Mattur C.
    In many nuclear installations like particle accelerators and medical cyclotrons, concrete has been used as a radiation shield due to its gamma and neutron radiation shielding capabilities. The gamma radiation shielding properties of concrete mixes are found to be enhanced by using high density ingredients. It has been professed that the neutron radiation shielding properties can be enhanced by use of ingredients containing higher amounts of lighter elements like hydrogen and boron. In the present work, attempts are made to use alternative materials as additional hydrogen sources within the concrete mixes and evaluate their effectiveness in enhancing the neutron radiation shielding properties. In the first phase, commercially available Styrene Butadiene Rubber (SBR) latex was used to produce latex modified concrete mixes and their neutron shielding capabilities were evaluated. It is observed that the latex modified mixes showed enhanced neutron shielding capabilities reflected in terms of lower dose transmission values vis- à-vis a control concrete mix. In the second phase, pulverized high density polyethylene (HDPE) was used as a partial replacement (replacement in the range of 30-50% by volume) to the fine aggregate fraction of the concrete mix. It was necessary to proportion these mixes as a class of self compacting concrete mixes so as to restrict the segregation behavior of the polymeric particles, in such Polymer Incorporated Self Compacting Concretes (PISCC) mixes. The segregation characteristics of PISCC mixes are found to be within allowable limits, their fresh properties and the mechanical strength properties are satisfactory. It is found that such PISCC mixes have significantly improved neutron shielding performances. Though there are improvements in the attenuation of neutron flux, the PISCC mixes are in particular, more effective in reducing the neutron dose rates. In the final phase, efforts were made to incorporate high density aggregates (both fine and coarse) so as to enhance the shielding properties and produce highly flowing concrete mixes. The maximum polymer replacement was retained; high density fine and coarse aggregates and a small amount of borax were added. Based on the detailed experimental investigations, recommendations are made to design such class of mixes so as to have good slump flows (> 400mm) and better segregation resistance characteristics. The studies on neutron radiation shielding characteristics indicated greater improvements in the shielding properties with a maximum of 12.7% reduction in half value layer (HVL) thickness for neutron radiation. The gamma radiation shielding studies of these mixes have also indicated significant improvements with a maximum of 13.7% reduction in HVL thickness.
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    Synthesis of Some New Pyrazole Derivatives and Their Antituberculosis Screening
    (National Institute of Technology Karnataka, Surathkal, 2017) Nandam, Harikrishna; Isloor, Arun M.
    Antibiotics improve the better living life in the world for human as well as animals. Many types of bacteria are dramatically reduces illnesses and deaths caused by various infections. Therefore, it occupies great importance to discover newer, effective and safer drugs in the modern world. In the last few decades, the process of drug discovery program has undergone fundamental transformation to synthesize customs molecules and new chemical entities (NCEs). Organic synthesis approaches towards designing, innovation and low molecular chemical structures, which are easily available, biologically active, will definitely aid in combating the ailments prevailing universally. Although, the increasing cost for discovery of such molecules in terms of research and development, analysis, in vitro and in vivo studies for new sites were worries the pharmaceutical research. Newer heterocyclic compounds are being employed constantly in the hope of striking a proper perspective in combating the pathogen bacterial infections. A systemic investigation of this class of heterocyclic lead revealed that, pyrazole and its derivatives are well known nitrogen containing heterocyclic compounds occupy an important role in medicinal chemistry with wide variety of biological properties. Owing to this therapeutic degree of pyrazole and its derivatives, in the current research work, it has been planned to find out various potent heterocyclic moieties with pyrazole through active functional systems to form a new molecular framework. Accordingly, different libraries of pyrazole based compounds comprising of thiazole (T1-12), pyrazoline (T13-27), 1,4-dihydropyridine (T28-45), 1,3,4-oxadiazole (T46-54), [1,2,4]triazolo[3,4-b] [1,3,4]thiadiazole (T55-63), benzimidazole (T64-79) and trifluoromethylbenzyloxy derivatives (T80-97) have been designed and synthesized. Newly synthesized chemical derivatives were confirmed by various spectroscopic techniques viz. FT-IR, 1H-NMR, 13C-NMR, LC-MS and elemental analyses. Additionally, three dimension structures of few molecules were confirmed by single crystal X-ray diffraction (S-XRD) studies. Further, the target compounds were subjected to screen preliminary in vitro antitubercular, antibacterial and antifungal activities. The active molecules were identified and tested for their cytotoxicity studies against non-cancerous cells.
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    Performance Appraisal of Eco-Friendly Mortars and Concretes
    (National Institute of Technology Karnataka, Surathkal, 2018) Prabhu, K. Rajendra; Yaragal, Subhash C; Venkataramana, Katta
    Cement concrete is the major construction material largely used throughout the world for infrastructures like buildings, pavements, irrigation structures and so on. Concrete is prepared by using locally available materials. One of the important concern facing construction industry today is, the scarcity of virgin materials due to their exponential depletion and continued increase in demand. This is due to rapid growth in construction industry and stringent environmental policies to check and control harmful effects on environment, caused by production or processing methods for construction materials and chemicals. As the natural resources are fast depleting and also the production of cement and aggregates consume energy (energy intensive) which also indirectly produce carbon dioxide posing threat to the environment. Due to the above pressing needs, it is most warranted to search for alternative or promising eco-friendly materials. Huge amount of wastes generated in various fields is not utilized other than for land filling, incineration etc. These wastes can be utilized as ingredients partially or fully by embedding these wastes in either mortars or concretes without being detrimental. Experiments with Broken Mangalore Tiles (BMT) wastes in the form of Secondary Cementitious Material (SCM), Fine Aggregates (FA), and Coarse Aggregates (CA) were planned and executed to replace cement, river sand and granite CA respectively, to study the performance of both BMT based mortars and BMT based concretes. Further experiments have also been conducted to ascertain performance of BMT based mortars and BMT based concretes at elevated temperatures. Usage potential of BMT CA, in pervious concretes is studied. The scope for utilizing Iron Ore Tailings (IOT) and / or Copper Slag (CS) as replacement to River Sand (RS) is also assessed. Further Melt Processed Plastic (MPP) pellets as filler in mortar and concrete is attempted. Use of EPS packaging material as FA (as filler) and CA (as filler) is also undertaken in this investigation. Results show, with BMT waste material as fine aggregate or coarse aggregate to the extent of 100% replacement is possible without compromise on concrete strength,with 90 days of curing. It is interesting to note also that 100% FA and 100% CA could be replaced by 100% BMT FA and 100% BMT CA without loss in concrete strength with 90 days of curing. Even in the case of mortar, there is no loss in strength for mortar with 100% BMT FA, with 90 days curing. 80% addition of BMT powder or 20% replacement of cement by BMT powder with 90 days curing is possible without loss in mortar strength. 100% BMT CA, based concrete has given higher endurance to elevated temperatures as regards to strength. Loss in weight increases with both rise in temperature as well as increase in the BMT CA content. Higher BMT CA increases porosity and assists better elevated temperature endurance. Up to 600°C, the performance of concrete with BMT FA (either half or full replacement) is superior when compared to concrete with 0% BMT FA. Higher BMT FA increases porosity indirectly favouring better elevated temperature endurance up to 600°C. For BMT FA and BMT CA based concrete at elevated temperatures, residual compressive strength remains nearly constant up to 400°C. Further increase in temperature up to 800°C, strength decreases. However, the differences in strengths between various combinations reduce after 400°C. Residual strength of mortar mix BMT FA100, monotonically decreases with increase in temperature. However its performance appears to be better than mortar mix BMT FA50 for temperature levels of 600°C and 800°C. It is observed that mortar with BMT powder as addition to OPC possesses more strength than replacement to OPC at all levels of temperatures. For a given porosity, the density of pervious concrete with BMT CA is always lower than that of granite CA by around 300 kg/cu.m. BMT CA in full replacement to granite CA, performs well in pervious concretes. Compressive strength of concrete reduces by about 26% when sand is replaced from 0 to 100% by IOT. Strength values almost remain constant up to 75% replacement of sand by IOT. Copper slag replacing sand to the extent of 100% does not result in strength reduction of concrete. From mortar strength studies with IOT and CS in place of sand, it is to be noted that for both cases replacement level of 50%, result in no loss in strength with two months of curing period. MPP pellets are added as filler by volume of concrete. It isobserved that the concrete strength drops by 50% for approximately 25% filler. Strength variation of mortars containing river sand, IOT and CS as FA with MPP pellets as filler at different blending dosages is studied. For all the three cases strength drops with increase in filler content, however the rate of drop is lower for mortar containing IOT as FA and higher for CS as FA, when compared to mortar with RS as FA. For concrete, with increase in EPS CA (as filler) content, all the three strengths (compression, split tensile and flexural) decrease by about 70-80% for 100% replacement. For mortar, as EPS FA (as filler) content increase, there is decrease in strength. At 100% replacement, the strength is approximately 15% of the reference mortar strength. This study is a step towards sustainable construction practices and recommends use of these eco-friendly unconventional materials to the extent possible.