Abstract: | Study on variable stars is an important topic of modern astrophysics. After the invention of powerful telescopes and high resolving powered CCD’s, the variable star data is accumulating in the order of peta-bytes. The huge amount of data need lot of automated methods as well as human experts. This thesis is devoted to the data analysis on variable star’s astronomical time series data and hence belong to the inter-disciplinary topic, Astrostatistics. For an observer on earth, stars that have a change in apparent brightness over time are called variable stars. The variation in brightness may be regular (periodic), quasi periodic (semi-periodic) or irregular manner (aperiodic) and are caused by various reasons. In some cases, the variation is due to some internal thermo-nuclear processes, which are generally known as intrinsic vari- ables and in some other cases, it is due to some external processes, like eclipse or rotation, which are known as extrinsic variables. Intrinsic variables can be further grouped into pulsating variables, eruptive variables and flare stars. Extrinsic variables are grouped into eclipsing binary stars and chromospheri- cal stars. Pulsating variables can again classified into Cepheid, RR Lyrae, RV Tauri, Delta Scuti, Mira etc. The eruptive or cataclysmic variables are novae, supernovae, etc., which rarely occurs and are not periodic phenomena. Most of the other variations are periodic in nature. Variable stars can be observed through many ways such as photometry, spectrophotometry and spectroscopy. The sequence of photometric observa- xiv tions on variable stars produces time series data, which contains time, magni- tude and error. The plot between variable star’s apparent magnitude and time are known as light curve. If the time series data is folded on a period, the plot between apparent magnitude and phase is known as phased light curve. The unique shape of phased light curve is a characteristic of each type of variable star. One way to identify the type of variable star and to classify them is by visually looking at the phased light curve by an expert. For last several years, automated algorithms are used to classify a group of variable stars, with the help of computers. Research on variable stars can be divided into different stages like observa- tion, data reduction, data analysis, modeling and classification. The modeling on variable stars helps to determine the short-term and long-term behaviour and to construct theoretical models (for eg:- Wilson-Devinney model for eclips- ing binaries) and to derive stellar properties like mass, radius, luminosity, tem- perature, internal and external structure, chemical composition and evolution. The classification requires the determination of the basic parameters like pe- riod, amplitude and phase and also some other derived parameters. Out of these, period is the most important parameter since the wrong periods can lead to sparse light curves and misleading information. Time series analysis is a method of applying mathematical and statistical tests to data, to quantify the variation, understand the nature of time-varying phenomena, to gain physical understanding of the system and to predict future behavior of the system. Astronomical time series usually suffer from unevenly spaced time instants, varying error conditions and possibility of big gaps. This is due to daily varying daylight and the weather conditions for ground based observations and observations from space may suffer from the impact of cosmic ray particles. Many large scale astronomical surveys such as MACHO, OGLE, EROS, xv ROTSE, PLANET, Hipparcos, MISAO, NSVS, ASAS, Pan-STARRS, Ke- pler,ESA, Gaia, LSST, CRTS provide variable star’s time series data, even though their primary intention is not variable star observation. Center for Astrostatistics, Pennsylvania State University is established to help the astro- nomical community with the aid of statistical tools for harvesting and analysing archival data. Most of these surveys releases the data to the public for further analysis. There exist many period search algorithms through astronomical time se- ries analysis, which can be classified into parametric (assume some underlying distribution for data) and non-parametric (do not assume any statistical model like Gaussian etc.,) methods. Many of the parametric methods are based on variations of discrete Fourier transforms like Generalised Lomb-Scargle peri- odogram (GLSP) by Zechmeister(2009), Significant Spectrum (SigSpec) by Reegen(2007) etc. Non-parametric methods include Phase Dispersion Minimi- sation (PDM) by Stellingwerf(1978) and Cubic spline method by Akerlof(1994) etc. Even though most of the methods can be brought under automation, any of the method stated above could not fully recover the true periods. The wrong detection of period can be due to several reasons such as power leakage to other frequencies which is due to finite total interval, finite sampling interval and finite amount of data. Another problem is aliasing, which is due to the influence of regular sampling. Also spurious periods appear due to long gaps and power flow to harmonic frequencies is an inherent problem of Fourier methods. Hence obtaining the exact period of variable star from it’s time series data is still a difficult problem, in case of huge databases, when subjected to automation. As Matthew Templeton, AAVSO, states “Variable star data analysis is not always straightforward; large-scale, automated analysis design is non-trivial”. Derekas et al. 2007, Deb et.al. 2010 states “The processing of xvi huge amount of data in these databases is quite challenging, even when looking at seemingly small issues such as period determination and classification”. It will be beneficial for the variable star astronomical community, if basic parameters, such as period, amplitude and phase are obtained more accurately, when huge time series databases are subjected to automation. In the present thesis work, the theories of four popular period search methods are studied, the strength and weakness of these methods are evaluated by applying it on two survey databases and finally a modified form of cubic spline method is intro- duced to confirm the exact period of variable star. For the classification of new variable stars discovered and entering them in the “General Catalogue of Vari- able Stars” or other databases like “Variable Star Index“, the characteristics of the variability has to be quantified in term of variable star parameters. |
URI: | http://dyuthi.cusat.ac.in/purl/4978 |
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Dyuthi-T2049.pdf | (19.62Mb) |
Abstract: | HINDI |
Description: | Department of Hindi, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/4792 |
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Dyuthi-T1889.pdf | (9.649Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5114 |
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Dyuthi-T 2179.pdf | (4.590Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5298 |
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Dyuthi T-2334.pdf | (9.367Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5425 |
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Dyuthi T-2467.pdf | (536.9Kb) |
Abstract: | This thesis comprises five chapters including the introductory chapter. This includes a brief introduction and basic definitions of fuzzy set theory and its applications, semigroup action on sets, finite semigroup theory, its application in automata theory along with references which are used in this thesis. In the second chapter we defined an S-fuzzy subset of X with the extension of the notion of semigroup action of S on X to semigroup action of S on to a fuzzy subset of X using Zadeh's maximal extension principal and proved some results based on this. We also defined an S-fuzzy morphism between two S-fuzzy subsets of X and they together form a category S FSETX. Some general properties and special objects in this category are studied and finally proved that S SET and S FSET are categorically equivalent. Further we tried to generalize this concept to the action of a fuzzy semigroup on fuzzy subsets. As an application, using the above idea, we convert a _nite state automaton to a finite fuzzy state automaton. A classical automata determine whether a word is accepted by the automaton where as a _nite fuzzy state automaton determine the degree of acceptance of the word by the automaton. 1.5. Summary of the Thesis 17 In the third chapter we de_ne regular and inverse fuzzy automata, its construction, and prove that the corresponding transition monoids are regular and inverse monoids respectively. The languages accepted by an inverse fuzzy automata is an inverse fuzzy language and we give a characterization of an inverse fuzzy language. We study some of its algebraic properties and prove that the collection IFL on an alphabet does not form a variety since it is not closed under inverse homomorphic images. We also prove some results based on the fact that a semigroup is inverse if and only if idempotents commute and every L-class or R-class contains a unique idempotent. Fourth chapter includes a study of the structure of the automorphism group of a deterministic faithful inverse fuzzy automaton and prove that it is equal to a subgroup of the inverse monoid of all one-one partial fuzzy transformations on the state set. In the fifth chapter we define min-weighted and max-weighted power automata study some of its algebraic properties and prove that a fuzzy automaton and the fuzzy power automata associated with it have the same transition monoids. The thesis ends with a conclusion of the work done and the scope of further study. |
URI: | http://dyuthi.cusat.ac.in/purl/4938 |
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Dyuthi-T2016.pdf.pdf | (648.9Kb) |
Abstract: | This research was undertaken with an objective of studying software development project risk, risk management, project outcomes and their inter-relationship in the Indian context. Validated instruments were used to measure risk, risk management and project outcome in software development projects undertaken in India. A second order factor model was developed for risk with five first order factors. Risk management was also identified as a second order construct with four first order factors. These structures were validated using confirmatory factor analysis. Variation in risk across categories of select organization / project characteristics was studied through a series of one way ANOVA tests. Regression model was developed for each of the risk factors by linking it to risk management factors and project /organization characteristics. Similarly regression models were developed for the project outcome measures linking them to risk factors. Integrated models linking risk factors, risk management factors and project outcome measures were tested through structural equation modeling. Quality of the software developed was seen to have a positive relationship with risk management and negative relationship with risk. The other outcome variables, namely time overrun and cost over run, had strong positive relationship with risk. Risk management did not have direct effect on overrun variables. Risk was seen to be acting as an intervening variable between risk management and overrun variables. |
Description: | School of Management Studies, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/xmlui/purl/1932 |
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Dyuthi-T0479.pdf | (1.953Mb) |
Abstract: | This thesis analyzed waste generation and waster disposal problems in municipalities and Cochin Corporation in Ernakulam district.Then the potential of resource recovery and recycling from biodegradable and non bio-degradable waste is established.The study further focused on the need for segregation of waste at the source as biodegradable and non biodegradable solid waste.The potential of resource recovery is explained in detail through the case study.The thesis also highlights the economically viable and environmental friendly methods o f treatment of waste.But the problem is that concerted and earnest attempts are lacking in making use of such methods.In spite of the health problems faced,people living near the dump sites are forced to stay there either because of their weak economic background or family ties.The study did not calculate the economic cost of health problems arising out of unscientific and irresponsible methods of waste disposal. |
Description: | Dept.of Applied Economics,Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2955 |
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Dyuthi-T0946.pdf | (22.29Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5565 |
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Dyuthi T-2607.pdf | (1.534Mb) |
Abstract: | A sensitive method based on the principle of photothermal phenomena to study the energy transfer processes in organic dye mixtures is presented. A dual beam thermal lens method can be very effectively used as an alternate technique to determine the molecular distance between donor and acceptor in fluorescein–rhodamine B mixture using optical parametric oscillator. |
URI: | http://dyuthi.cusat.ac.in/purl/2416 |
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Dyuthi-P0257.pdf | (172.7Kb) |
URI: | http://dyuthi.cusat.ac.in/purl/1609 |
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A study on the ... idukki district,Chap-1.PDF | (19.33Mb) |
A study on the ... idukki district,Chap-2.PDF | (23.05Mb) |
A study on the ... idukki district,Chap-3.PDF | (27.94Mb) |
A study on the ... idukki district,Chap-4.PDF | (11.18Mb) |
A study on the ... idukki district,Chap-5.PDF | (13.53Mb) |
A study on the ... idukki district,Chap-6.PDF | (13.94Mb) |
A study on the ... idukki district,Chap-7.PDF | (14.19Mb) |
A study on the ... idukki district,Chap-8.PDF | (11.50Mb) |
A study on the ... idukki district,Chap-9.PDF | (11.84Mb) |
Abstract: | This study focuses on psychological empowerment of employees in banking sector because of the reasons stated below: Firstly, very little research has been conducted in understanding empowerment as a psychological construct. Majority of the studies have been conducted on the various empowerment practices in the organizations. Secondly, there is no empirical evidence that the empowerment practice will create a subjective feeling of empowerment within the individual. Employee empowerment will be effective only if the employees actually experience the empowerment. Even if the organizations have the empowerment practices like providing power and open communication it is not necessary that the employee is empowered. Empowerment describes only the condition of work environment. It does not describe employees’ response to these conditions. These responses form the basis for psychological empowerment |
URI: | http://dyuthi.cusat.ac.in/purl/5053 |
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Dyuthi- T 2120.pdf | (2.216Mb) |
Abstract: | The present research is carried out to understand how psychological empowerment, job satisfaction and job related stress are related.In banking sector, employees are less satisfied and less motivated than employees in other lines of work (Kelley, 1990; Bajpai, Naval and Deepak, 2004). The banking industry also suffers from high employee turnover rate (Branham, 2005; Nelson, 2007) and high level of stress (Chen and Lien, 2008). There are no adequate studies linking psychological empowerment and job satisfaction, stress, turnover etc. among employees of banking sector. Lack of psychological empowerment could be a reason for these problems faced by banking sector. Further majority of studies in psychological empowerment are carried out in manufacturing sector and studies in service sector are concentrated on hotel industry and hospitals. Empowerment takes different forms in different contexts (Zimmerman, 1995). In the light of above discussion, the present research is directed to explore the dimensions of psychological empowerment of employees in banking sector and to find out whether high psychological empowerment can increase job satisfaction and reduce job related stress among employees in banking sector |
Description: | Department of Applied Economics Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3809 |
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Dyuthi-T1740.pdf | (2.230Mb) |
Description: | Department of Applied Economics,Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2662 |
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Dyuthi-T0714.pdf | (3.851Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5477 |
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Dyuthi T-2519.pdf | (11.48Mb) |
Abstract: | The constructional activities in the coastal belt of our country often demand deep foundations because of the poor engineering properties and the related problems arising from weak soil at shallow depths.The soil profile in coastal area often consists of very loose sandy soils extending to a depth of 3 to 4 m from the ground level underlain by clayey soils of medium consistency.The very low shearing resistance of the foundation bed causes local as well as punching shear failure.Hence structures built on these soils may suffer from excessive settlements.This type of soil profile is very common in coastal areas of Kerala,especially in Cochin. Further,the high water table and limited depth of the top sandy layer in these areas restrict the depth of foundation thereby further reducing the safe bearing capacity. |
Description: | Division of Civil Engineering,Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2348 |
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Dyuthi-T0623.pdf | (4.527Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/2966 |
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Dyuthi-T0955.pdf | (5.035Mb) |
Abstract: | This work was focused to study the immobilization of enzymes on polymers. A large range of polymer matrices have been employed as supports for enzyme immobilization. Here polyaniline (PAN!) and poly(0~toluidine) (POT) were used as supports. PANI and POT provides an excellent support for enzyme immobilization by virtue of its facile synthesis, superior chemical and physical stabilities, and large retention capacity. We selected industrially important starch hydrolyzing enzymes a-amylase and glucoamylase for the study. In this work the selected enzymes were immobilized via adsorption and covalent bonding methods.To optimize the catalytic efficiency and stability of the resulting biocatalysts, the attempt was made to understand the immobilization effects on enzymatic properties. The effect of pH of the immobilization medium, time of immobilization on the immobilization efficiency was observed. The starch hydrolyzing activity of free 0:-amylase and glucoamylase were compared with immobilized forms. Immobilization on solid supports changes the microenvironment of the enzyme there by influences the pH and temperature relationship on the enzymatic activity. Hence these parameters also optimized. The reusability and storage stability of immobilized enzymes an important aspect from an application standpoint, especially in industrial applications. Taking in to consideration of this, the reusability and the long tenn storage stability of the immobilized enzyme investigated. |
Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2846 |
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Dyuthi-T0855.pdf | (4.593Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5273 |
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Dyuthi T-2309-1.pdf | (38.57Mb) |
Dyuthi T-2309-2.pdf | (208.2Kb) |
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