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Social media campus party politics and political participation
Political Participation is a desired quality among citizens in a democracy. Earlier studies have indicated that Political Knowledge, Political Efficacy and Civic Engagement enhance the Political Participation of college students. The current study has its background in two key aspects in the Indian context: First, the proliferation of Social Media Usage among newlinecollege students in the last decade; Second, the implementation of the Lyngdoh Commission Report (May 2006) on Campus Party Politics. newlineStudies have not adequately addressed the question of the direct impact of Social Media Usage among college students, on their level of Political Knowledge, Political Efficacy, Civic Engagement, and Political newlineParticipation. The present study attempts to assess the impact of Social Media Usage on Political Knowledge, Political Efficacy and Civic Engagement and Political Participation of college students in the context of Kerala. In the context of the implementation of the Lyngdoh Commission report by some of the college and University campuses in India thus banning Party Politics in their campuses, while some of the other campuses still retaining Campus Party Politics, the newlinepresence/absence of Campus Party Politics is used as a control variable to see the impact of Campus Party Politics on Social Media Usage, Political Knowledge, Political Efficacy, Civic Engagement, and Political newlineParticipation. To check the impact of various factors on Political Participation, a path model is framed and analysed using Structural newlineEquation Modelling. Key demographic variables such as gender, political student union membership, type of management that own and operate the college, the stream of study of students, etc are also examined to see its newlinevarying effects on the key variables under consideration. The results indicate that Social Media Usage and Political Knowledge do not impact Political Participation while Political Efficacy and Civic Engagement do newlineimpact Political Participation. -
Software bug in identification and prediction through software are metrics in object oriented protects :
In the software engineering, quality assurance plays an important role. newlineThe quality assurance as an activity, observes the execution of software project to ensure that the behavior of product is in accordance with the expectations. The testing is associated with quality assurance activities. The testing takes a lot of time and an effort of the tester to test the test newlinecases. Even after enough manual or automatic testing, bugs remain uncovered because of lack of time. So, a need arises to focus on this area to save the time and cost of the organizations. The software developer or newlinetester should be aware about the main reasons of software bugs so that they can focus on the right part of the code at the right time. Need of introducing product, process and project metrics is also very essential for newlinethe identification of major causes of bugs. Predictions will always be best if the history of project is taken into consideration. We can come up with accurate predictors with the help of root causes of the software bugs. Several bug prediction models can use bug indicators as the input of model to predict the number of bugs. newlinePrediction attempts to provide quantitative measures to help the software testers and developers. With more number of bug indicators, a step can be taken towards wider horizon of bug prediction thus enabling higher devotion to improve quality of software products. Therefore, identification of several reasons of software bugs and implementation of effective bug prediction models are needed to widen the scope of bug newlineprediction approaches and to improve the software quality. After estimating the future bugs using prediction models, awareness of bug severity is also required to avoid the expected harms to software products. newlineIntroduction of Artificial Neural Network (ANN) was needed to improve the prediction potential. In this work an attempt has been made to associate different levels and types of inheritance through neural network newlineby establishing a correlation framework with diverse types of bug severitie. -
Spatio temporal crime analysis and forecasting using social media data
Now a days, people communicate, share ideas, and interact through social media platforms. It has given us an ability to talk about career interests, post videos, and pictures for sharing with others. The data present in social media enables the analysis of various human aspects. The social media data and domain is used for crime analysis, customer behaviour analysis, and healthcare analysis provides much information useful to predict human behaviours. Crime is the most common social problem faced in a developing country. In developing countries like India, crime plays a detrimental role in economic growth and prosperity. With the increase in delinquencies, law enforcement needs to deploy limited resources optimally to protect citizens. Crime affects the reputation of a nation and the quality of life of its citizens. Crime also affects the economy of the country, increasing the financial burden of the government due to the need for expenditure in the police force and judicial system. Various initiatives are taken by law enforcement to reduce the crime rate. An example of these initiatives includes an accurate and real-time prediction of crime occurrences. Crime analytics and prediction have lengthily studied among research analytics communities. In recent years, crime knowledge from one of a kind heterogeneous source (Twitter, News Feeds, Facebook, Instagram and so forth.) have given enormous opportunities to the research group to comfortably study crime pattern and prediction duties in specific real knowledge. Data mining and predictive analytics provide the best options for the same. Law enforcement organizations are increasingly looking to use data from social media such as Facebook, Newsfeeds, Twitter, etc. investing in research in this area. Using the intelligence gained through these data, the agencies can identify future incidents and plan for active patrolling. -
Spectral and Timing Properties of Selected Black Hole Binaries
X-ray binaries hosting a black hole (accretor) and a main sequence or a post-main sequence star (companion star) are called black hole X-ray binaries (BHXBs). BHXBs are gravitationally bound systems where the matter from the companion star is accreted onto the accretor either via a Roche lobe overand#64258;ow (low-mass companion star) or stellar wind (high-mass companion star). The accreted matter spirals towards the accretor, losing its angular momentum in the process. The gravitational potential energy of the in-falling matter is converted to kinetic energy which is eventually released as X-rays. X-ray spectrum of BHXB is quite complex by nature, which is contributed by various X-ray production processes. Systematic and comprehensive investigations of the X-ray production mechanisms are essential for understanding the fundamentals of accretion physics and exploring the general relativistic effects in extreme gravity environments. Launch of several dedicated X-ray missions like Uhuru, Ginga, RXTE, Chandra, XMM-Newton, NuSTAR, Swift, etc. for over half a century have led to the discovery, classifcation and fair understanding of spectro-temporal properties of BHXBs. Despite the continuous and ongoing newlineefforts, the physics of the accretion mechanism in BHXBs, accretion disk geometry, the origin of quasi periodic oscillations (QPOs), energy-dependent time lags and coherence of X-ray photons in different energies, etc., are yet to be completely understood. Hence, there is a need for newlinerevisiting these problems using the data from more sensitive instruments, that have broadband energy coverage and have better spectral and timing resolutions than RXTE. Thus, data from the latest missions like AstroSat, Swift, NuSTAR with their broadband energy coverage, especially in the lower energy regime (and#8804; 3.0 keV), and larger effective area can help fll in the gap in the newlineexisting body of knowledge and provide a holistic understanding of these sources. -
Spectroscopic Studies and Theoretical Analysis of Some Selected Heterocycles
Seven derivatives of heterocycles benzimidazole, benzoxazole and benzothiazole were studied, five of which were synthesized and characterized. The molecular geometry and newlinespectroscopic data of the compounds in the ground state were calculated using the density functional theory (DFT/B3LYP) method with the 6-311++G(d,p) basis set. A comparison between the experimental and calculated data was attempted. Molecular electrostatic potential (MEP) and global reactivity parameters were deduced using theoretical calculations. HOMO-LUMO energy gap for each compound was determined by DFT and cyclic voltammetry. The cyclic voltammograms were recorded in acetonitrile solvent using lithium perchlorate as the supporting electrolyte. For all the compounds experimentally determined HOMO LUMO energy gap in polar solvent was lesser than that from DFT calculated energy gap. Using the HOMO-LUMO energy gap, global reactivity parameters were calculated. The effect of solvents of varying polarity on the absorption and emission spectra of the compounds was studied. Large excitation and emission energy differences were observed for all the selected heterocycles. The excitation and fluorescence spectra of selected heterocycles were recorded in eight solvents of different solvent polarity. It is evident from the excitation spectra that on increase of the solvent polarity, a bathochromic shift takes place for and#960;-and#960;* transition, and this is attributed to the high influence of solvent polarity in the excited state of heterocycle newlinecompared to its ground state. The dipole moments in the ground and the first excited state of heterocycle derivatives were newlinecalculated using Lippert-Mataga and Kawski-Chamma-Viallet methods. Guggenheim-Debye method was adopted to calculate ground state dipole moment. The dipole moments of the compounds were also calculated using Time Dependent-Density Functional Theory (TD-DFT). The dipole moment values of the compounds suggested that the excited state has more charge separation and thus becomes more polar. -
Strategies to manage power outages and optimize energy cost for developing countries through supply and demand side management
Developing Countries like India, face huge amounts of power cuts starting from a few hours to few days. Some of the main reasons are transmission and distribution losses, theft, lack of smart infrastructure, poor newlinemaintenance of the existing systems, lack of smart algorithms etc., Due to this reason consumers have moved to back up systems to feed their loads. Tonnes of diesel has been consumed through generators, due to power cuts, because to this consumers are suffering to pay extra cost for electricity as their energy bills are an addition of grid cost as well as the back up cost.The load dispatch centers will implement load shedding leading to a compete outage in a few areas. As a result the consumers in these areas newlineimmediately turn on their back up sources leading to an increase in energy cost. There are no smart algorithms used either to distribute the power at the utility end or to manage the loads during an outage, especially when the loads are running on back-up supply. This report suggests some smart algorithms to provide partial power to consumers rather than a complete outage, load shifting techniques to the consumers at the time of an outage so that they can optimize their back up cost, last but not the least smart newlineintegration of solar power to the consumers to optimize the over all energy costs. newlineThe partial outage algorithm results, in supplying partial power to consumers rather than a complete outage condition this is achieved by implementing a simple unitary method based on the power consumption of the newlineconsumers. By supplying partial power, the consumers can save a certain amount of expenditure on back up cost especially from diesel generators and also utilize the on grid solar generation if the consumer is having a solar roof top installation. -
Strategy formulation and implementation in the zimbabwean food manufacturing sector
This study focused on examining the influence of strategy formulation and implementation on the performance and competitive advantage of the foodmanufacturing companies in Zimbabwe. The study was prompted by the fact that newlinestrategy is essential in every organisation and that competing in the market is like newlinewar, you have injuries and casualties and the best strategy wins . More so, even though the food-manufacturing companies are essential to the Zimbabwean economy, there has been limited research on the area of strategy formulation and implementation. The study applied both quantitative and qualitative approaches because looking at the same problem from several viewpoints is an excellent way to verify data and come up with interpretation and conclusions. It is in view of this fact that the researcher used the triangulation approach, which is a combination of both philosophies, qualitative and quantitative data. The research was a survey because it allowed the research to collect data from a sizeable number of participants in 10 foodmanufacturing companies in Zimbabwe. The researcher used personal judgement in selecting the companies to be part of the study. The data was collected from directors and managerial employees, who are largely involved in the process of strategy formulation and implementation. The researcher used the questionnaires and the indepth interviews as research instruments. SPSS was the quantitative data analysis and qualitative data analysis was using thematic analysis. The study found out that foodmanufacturing companies in Zimbabwe were facing performance related challenges and there were mixed responses on the extent to which they were failing to meet financial, customer, internal business process improvement, and learning and growth targets. The food-manufacturing companies implemented marketing, human resource, financial and operations strategies but were not successful in their endeavours. -
Studey of different types of modulations on double diffusive convection in lodroyd-b liquids
The problem aims to find the effects of temperature modulation in viscoelastic newlinefluids namely Oldroyd B liquids subjected to double diffusive convection. Both linear as well as a non-linear study has been carried out. A regular perturbation technique has been employed to determine the correction Rayleigh number. The results show that the Lewis number and strain retardation parameter induces stability to the system whereas stress relaxation parameter destabilizes the system for synchronous modulation. Truncated Fourier series represents the non-linear newlineanalysis. Mean Nusselt number and mean Sherwood number are used to quantify the newlineheat and mass transfer respectively. Strain retardation parameter and the Lewis number decrease the heat and mass transfer for synchronous modulation while stress relaxation parameter increases them. The opposite results are obtained for newlineasynchronous and lower wall modulations. Modulation is shown mostly to give rise newlineto super critical motion. -
Studies on color energy and its variations in graphs
This thesis consists of studies on color energy and its variations in graphs. Apart from the exploration of color energy corresponding to various coloring schemes, the notion of P-energy as a generalization of color energy has been introduced. The computation of color energy and P-energy of graphs has been carried out using Python programs, while the general results are derived using research methods and proof techniques in linear algebra. The bounds of color energy for a graph G have been established in terms of several graph parameters such as chromatic number and#967;(G), domination number and#947;(G), maximum degree and#8710;(G) etc. It has been found out that the color energy of a graph G is greater than or equal to 1 n and#947;(G) q 2(m + mand#8242;c). Further, the bounds of color energy of a graph G in terms of extreme eigenvalues of color matrix of G have been obtained. The study on color energy with respect to the minimum number of colors and L(h, k)-coloring has been examined in detail for some families of graphs such as star graph, double star, crown graph and their color complements. We have also examined the variation of color energy in the specific cases of T-coloring and radio coloring for some families of graphs. The examination of color energy corresponding to some improper colorings such as Hamiltonian coloring, open neighborhood coloring and improper C-coloring has also been done. Moreover, the color equi-energetic families of graphs with respect to various coloring schemes have been investigated. The concept of P-energy has been introduced as a generalization of the concept of color energy. This stems from the fact that coloring problems in essence are vertex partition problems. For any vertex partition P having k elements, we define the P-matrix AP(G) having and#8722;1, 0, 1, 2 as off diagonal entries and diagonal entries represent the cardinality of the elements in partition P. Then, the P-energy EP(G) is defined as the sum of the absolute values of eigenvalues of P-matrix of G. -
Studies on dark matter dark energy and possible alternate models
The nature of dark matter (DM) and dark energy (DE) which is supposed to constitute about 95% of the energy density of the universe is still a mystery. There is no shortage of ideas regarding the nature of both. While some candidates for DM are clearly ruled out, there is still a plethora of viable particles that fit the bill. In the context of DE, while current observations favour a cosmological constant picture, there are other competing models which may be equally likely. The standard model for the formation of structure assumes that there newlineexisted small fluctuations in the early universe that grew due to gravitational instability. The origin of these fluctuations are still unclear. In this study, we proposed the role of dark matter in providing the seed for star formation in the early universe, which is supported by very recent observations. With this we set observable constraints on luminosities, temperatures, and lifetimes of the early stars with an admixture of dark matter. We also studied the effects of the background repulsive dark energy density for large scale cosmic structures. The relation, and#119872;and#8260;and#119877;2 and#8776; 1and#119892;/and#119888;and#119898;2, seems to hold true for primeval galaxies as well as those at present epoch. From this, we set constraints on the nature and evolution of dark energy. Besides, we also set constraints on the size of galaxy clusters and superclusters due to the repulsive cosmological dark energy. This could indicate as to why large scale cosmic structures much larger than and#8764;200 Mpc are not seen.This study also looked at the evolution of the concept of the cosmological constant from its inception a little over a hundred years ago when Einstein introduced the cosmological constant in his General Theory of Relativity newlinein order to obtain a static universe to conform to the philosophical view of newlinethe universe at that time to it possibly making up close to about 70% of the energy density of the universe. -
Studies on K X Ray fluorescence parameters of low and medium Z elements
K X-ray fluorescence parameters for pure elements have been determined using different single and double reflection geometry by several researchers over the years. Horakeri et al.have shown that the K X-ray fluorescence parameters can also be determined by a simple 2and#960;-geometrical configuration method and a NaI(Tl) detector spectrometer for high Z elements. newlineHowever, in order to study the K XRF parameters for low Z elements, high resolution detector spectrometers are required.But in high resolution detectors like HPGe and Si(Li), due to the gap between window and the active area of the detector, the solid angle subtended by the detector at the target is not 2and#960;. Hence a suitable geometry correction is required for accurate newlinemeasurement of incident photons and the emitted K X-ray photons in order to determine the K XRF parameters in low Z elements. In the present study, employing a nearly 2and#960;-geometrical configuration and applying suitable geometry correction, we have determined the K X-ray fluorescence parameters of a few low and medium Z elements in the range of 27 and#8804; Z and#8804; 30 and 42 and#8804; Z and#8804; 47 respectively. The elements were procured in the form of thin foils and were irradiated by a weak radioactive source. The emitted K X-ray photons were detected using a low energy high resolution HPGe detector spectrometer. The incident photons, emitted K X-ray photons and the transmitted photons at newlinethe incident energy is measured and were corrected for window attenuation, efficiency, self-attenuation and geometry correction newlineto obtain the true intensities of incident photons, emitted K Xray photons and the transmitted photons at the incident energy. -
Studies On Single Crystals and Thin Films of Tin Sulfide(SnS) For Photovoltaic Applications
The thesis is concerned with linear and nonlinear Rayleigh-Bard electroconvection in a horizontal porous layer. Modified Darcy law is employed to describe the fluid motion. The effect of non-classical heat conduction, chemical reaction, thermal radiation and finite amplitudes on the onset of Darcy electroconvection is considered. The findings of the problems investigated in the thesis may prove useful in heat transfer application situations with dielectric fluids as working medium. The summary of the problems addressed in the thesis is given below.Effect of non-classical heat conduction on Rayleigh-Bard newlineconvection in a horizontal layer of porous medium saturated with a dielectric fluid The method of small perturbations is used to examine the effect of non-classical heat conduction on the onset of Darcy electroconvection. Exact solutions for both stationary and oscillatory instability are obtained and known results have been deduced as limiting cases of the present study. It is shown that electroconvective instability in a Darcy porous layer is hastened by increasing the strengths of second sound and electric newlineforces and that the presence of second sound and dielectrophoretic force leads to shorter wavelength electroconvection. Further, it is found that the effect of Vadasz number is to advance the onset of oscillatory Darcy newlineelectroconvection and oscillatory instability sets in before stationary convection provided that the Vadasz number and the Cattaneo number are sufficiently large. Rayleigh-Bard convection in a horizontal layer of porous medium saturated with a chemically reacting dielectric fluid The problem of the effect of chemical reaction on the onset of Darcy electroconvection in a horizontal porous layer heated from below is newlineinvestigated. It is assumed that the fluid experiences a zero-order exothermic chemical reaction and that there exists a local thermal equilibrium between the fluid and the solid phases. -
Studies on the Culture Conditions, Nutritional Value of the Black Soldier Fly, Hermetia illucens (Diptera : Stratiomyid) and its Suitability as Aquaculture Feed
The Black Soldier Fly (BSF), Hermetia illucens, has emerged as a promising newlinesolution in aquaculture due to its remarkable ability to convert organic waste into newlineprotein-rich biomass. This has garnered interest among aquaculturists seeking costeffective and sustainable alternative ingredients for aqua feed. However, fully newlineharnessing the potential of this insect requires a deeper understanding of its life cycle and nutritional composition. A key challenge in utilising BSF larvae (BSFL) for newlineaquafeed production is the lack of standardized culture systems. This study addresses this gap by establishing a comprehensive culture system using two common organic wastes, fruit waste (FW) and vegetable waste (VW), as rearing substrates. By evaluating the growth performance of BSFL reared on these substrates, the research sheds light on optimal conditions for large-scale BSF production. The study investigated the impact of FW and VW substrates on BSFL growth through a thorough analysis of growth performance, morphometric measurements and newlineScanning Electron Microscopy (SEM). Results showed that BSFL reared on FW exhibited better growth (40 days) than those reared on VW (46 days). Morphometric analysis and SEM identified five larval stages and the prepupa, pupa, and adult stages. Additionally, the study analysed the nutritional composition of BSFL at different newlinedevelopmental stages, such as Instar 3 through instar 5, prepupa and pupa, including newlineprotein, carbohydrate, lipid, amino acids and fatty acids. This provided insights into newlinehow variations in substrate impact the nutritional quality of BSFL at different stages, which is crucial for ensuring that BSFL-derived feed meets the dietary requirements of target aquaculture species. Significant differences were found in the proximate composition of the substrates (FW and VW), resulting in significant variations in BSFL nutrition. BSFL reared on FW exhibited higher nutritional content especially crude newlineprotein (54.160.64%), than those reared on VW, except for crude lipids (2.200.01%). -
Studies on the Fresh Water Algal Floria in Chimmony Wildlife Sanctuary
Algae is a crucial organism in the environment. They help in maintaining the balance among different ecosystems. According to the geography and climatic conditions, newlineKerala has a suitable environment for algal growth. However, the algal biodiversity newlinestudies conducted in Kerala are significantly less. The wildlife sanctuary comprises a newlineconsiderable scope for algal biodiversity. The Chimmony wildlife sanctuary is situated in Mukundapuram taluk of Thrissur district. It spreads over 85.067 km2 with a water spread area of 10.1 km2. Ten different sampling stations were selected across newlinethe wildlife sanctuary, and extensive field visits were conducted to identify and newlinedocument the algae with respect to three seasons (pre-monsoon, monsoon, and post- newlinemonsoon). The physicochemical parameters of water like dissolved oxygen, temperature, pH, alkalinity, total dissolved solids, light intensity, and rainfall amount were estimated seasonally. In this present study, a total of 121 taxa belonging to 60 genera, 38 families, 24 orders, and 5 classes, namely Chlorophyceae, Bacillariophyceae, Euglenineae, Rhodophyceae, and Cyanophyceae, were identified from 10 different stations. The Bacillariophyceae and Chlorophyceae were the most dominant class in the study area. The algal multiplication will be more in the pre monsoon season and it was observed that the Chlorophyceaen members were dominant, while the Bacillariophyceae were dominant during the post-monsoon season. Cyanophyceae was dominant only during the monsoon season because of its sensitivity toward light. The ANOVA (Two-way) analysis showed no significant difference between stations, and there is a considerable difference between seasons for dissolved oxygen, alkalinity, temperature, and total dissolved solids. While pH, showed no significant difference between seasons and stations, light intensity showed a substantial difference between stations and seasons. The temperature and dissolved oxygen showed a negative correlation. -
Study of buoyancy and surface tension driven convention in nanaofluid
This thesis presents a detail study of linear and non-linear analysis of buoyancy and surface tension driven convection in nanofluid. The linear Rayleigh-Bard / Rayleigh- Bard Marangoni convection in nanofluids in the presence of external constraints like magnetic field, rotation and newlineinternal heat generation is investigated. The effect of temperature and volumetric concentration modulation of nanoparticles at the boundary and gravity modulation are studied on the onset of Rayleigh- Bard newlineconvection. The obtained results are discussed qualitatively and presented newlinegraphically. The problem discussed have important applications in the field of oceanography, geophysics, nuclear fuel, astrophysics, geothermal reservoirs, engineering and space situations with g-jitter connected with gravity simulation studies.Given the rising relevance of nanofluid application, we discuss four newlineproblems in this thesis whose detail summary is presented below: (i) LINEAR AND WEAKLY NON-LINEAR ANALYSIS OF GRAVITY MODULATION ON THE ONSET OF RAYLEIGH BARD CONVECTION IN NANOFLUID The effect of modulation of gravity or time-periodic body force on newlinethe onset of Rayleigh-Bard convection in nanofluid is studied using newlinelinear and non-linear analysis. The stability of the fluid layer heated from newlinebelow is analysed by considering time-periodic body acceleration. This newlinehappens generally in the vehicles and satellites associated with studies of newlinemicro gravity simulation. In order to study the effect of gravity modulation newlineon the system stability limit, linear and weakly non-linear analysis is performed. Normal mode technique and perturbation method is applied to study linear stability. The critical Rayleigh number and wave number is newlinecalculated by taking modulation of small amplitude. It is found that the critical thermal Rayleigh number can be increase or decrease by a massive amount depending upon the distribution of nanoparticles.In this thesis we considered bottom heavy distribution of nanoparticles. -
Study of Classical Be Stars in Open Clusters in the Galaxy
Classical Be stars (CBe) in open clusters older than 100 Myr are identifed. The objective is to study their characteristics relating to age, spectral type and evolutionary state. This study compliments with that of Mathew et al. (2008), where they identifed and characterized emission-line stars in open clusters younger than 100 Myr. For this research, we surveyed a sample of newline71 open clusters older than 100 Myr using the slitless spectroscopy technique, with the Himalayan Chandra Telescope (HCT). From the survey we identifed 15 CBe stars from the 11 open clusters older than 100 Myr. Out of 15 CBe stars, 13 CBe stars show Hand#945; in emission. Among these CBe stars, TYC 2679-432-1 is a new detection, belonging to Berkeley 50 open newlinecluster. Two more CBe stars, out of 15 CBe stars, are found to exhibit Hand#945; in absorption for the frst time. This suggests that they might be passing through a disc-loss episode (or transient phase). Apart from our survey of 71 old open clusters, we found additional 16 Be stars from 6 open clusters older than 100 Myr in the literature (which was not observed in the slitless survey due to observation limitations). In addition to HFOSC instrument mounted on HCT, we used Opto Mechanics Research (OMR) spectrograph newlinemounted on 2.3-m Vainu Bappu Telescope (VBT) for taking the slit spectra of CBe stars. We performed the optical spectroscopy of 16 classical Be stars in 11 open clusters older than 100 Myr. Among these 16 stars, 15 newlinewere identifed from our previous slitless spectroscopic study. The remaining one, LS III +47 37b is a new detection, which is confrmed through the present study. Our analysis also suggests that one out of these 16 stars, [KW97] 35-12 might be a weak Hand#945; emitter in nature showing Hand#945; EW of -0.5 Moreover, it is found that the Hand#945; EW for 15 stars is lt -40 in agreement with previous works. Interestingly, we did not observe any FeII emission line or even the OI 8446 emission feature in any of our sample stars. -
Study of Early-Type Emission -Line Stars in the Galaxy Using Lamost and GAIA
The study of massive emission-line stars (ELS), particularly those classifed as O, B, and A spectral types, is crucial in advancing our understanding of various fundamental aspects of astrophysics. They provide valuable insights into the accretion processes, the physical conditions of material around the star, and the stellar evolution. The frst theme of thesis focuses on identifying and characterising hot ELS newlinefrom large spectroscopic surveys such as LAMOST and Gaia DR3. Utilising the low-resolution spectroscopic database provided by LAMOST DR5, we employed an automated Python routine and identifed 3339 unique sources encompassing 4138 spectra that exhibited Hand#945; in emission. Since both HAeBe stars and Classical Ae/Be stars show Hand#945; emission, we differentiated them in terms of IR excess, from the analysis of 2MASS and WISE photometry. This analysis led to the identifcation of 1089 Classical Be stars, 233 Classical Ae stars, and 56 Herbig Ae/Be (HAeBe) stars. This homogeneous emission-line spectra will facilitate detailed investigations of the emission phenomenon, removing concerns related to data compilation newlinebiases from diverse sources. We also compared the astrophysical parameters obtained from Gaia DR3 with those derived from LAMOST spectra. The emission-line source classifcations in Gaia DR3 were reasonably consistent with those in the LAMOST OBA emission catalogue. Additionally, newlinewe used a larger dataset of ELS to update the empirical relation for converting pseudo-equivalent width to observed equivalent width in Gaia DR3, employing a second-degree polynomial relation and piece-wise linear ft newlineparameters. As the second theme of the thesis, we examined the X-Shooter spectral newlinedatabase to study the circumstellar medium of HAeBe stars through various spectral features and near-infrared excess. We observed that the ma-jority of massive and young stars exhibited emission in all higher-order HI newlinelines, while stars displaying only lower-order lines had effective temperatures below 12000 K and ages ranging from 5 to 10 Myr.