Lakshminath Bezbaroa Central Library Digital Repository
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Recent Submissions
Development of Kalman Filter based Algorithms for Fringe Pattern Analysis
(2024) Sharma, Shikha
The purpose of fringe pattern analysis is to retrieve the phase from the fringe pattern. The phase retrieval is essential from the fringe pattern in order to derive the object information. Therefore, demand for the phase information has promoted the development of fringe analysis techniques. Spatial fringe analysis techniques typically involve different operations such as fringe denoising, fringe normalization, and fringe pattern demodulation for the phase estimation. In some cases, phase aberration compensation is also required to be performed. The thesis presents a number of spatial fringe processing algorithms based on the application of Kalman filter.
Molecular Characterization of Begomoviruses Causing Yellow Mosaic Disease in Mungbean and Disease Management Through Biotechnological Intervention
(2024) Dhobale, Kiran Vilas
Yellow mosaic diseases (YMD), caused by Begomovirus, pose a significant threat to mungbean cultivation in the Indian subcontinent. This study investigates the epidemiology of begomovirus in three YMD hotspot regions, identifying Mungbean Yellow Mosaic Virus (MYMV) in Bihar and Mungbean Yellow Mosaic India Virus (MYMIV) in Assam and Orissa. The study explored the population structure and genetic diversity of MYMV and MYMIV isolates, revealing independent evolution of DNA-A and coevolution of DNA-B. To identify YMD-resistant mungbean genotypes, an agroinoculation-based genotype screening approach was employed. Using prepared infectious clones (MYMV and MYMIV) for screening YMD-resistant and susceptible mungbean genotypes, we identified genotypes highly susceptible to MYMV (cv. ML267) and MYMIV (cv. K851), as well as genotypes immune to MYMV (cv. PDM139, cv. SML668) and MYMIV (cv. Pusa Vishal). The study explores a non-transgenic approach for inducing resistance to YMD in mungbean. Two target regions within the viral genomes were identified for gene silencing using RNAi. We show that out of three intron hpRNAi constructs, namely hpTR-1: AC4/AC1, hpTR-2: AC2/AC3, and hpTR-1+2: AC4/AC1_AC2/AC3 (fusion construct), the hpTR-1+2 construct provided 100% protection, validated through a transient agroinfiltration assay. Subsequently, we show that in vivo synthesized hpRNA of hpTR-1+2 can persist and induce the generation of small interfering RNA (siRNA) in both local and systemic tissues for at least 12 days’ post-spray without viral inoculation, validated through semi-reverse transcription-PCR and northern blotting. Our data indicate that the naked hpRNA spray conferred resistance to MYMIV in mungbean, with the most significant inhibition of MYMIV replication observed when plants were treated on the same day, two days, and four days before viral inoculation. Furthermore, the study explored the role of the apoplast in Begomovirus infection. Importantly, we show the presence of genomic components of MYMIV in apoplastic fluid validated by molecular detection of viral genome through RCA and PCR analysis to enhance our understanding of the cell-to-cell movement of begomovirus via apoplast. Additionally, we have shown that virus infection induces elevated secretion of vesicles into the apoplast. NMR-based metabolomics analysis reveals altered metabolic profiles in both apoplast and symplast in response to MYMIV infection. Citrate downregulation and increased levels of valine, α-β-glucose, and pipecolic acid were observed in both compartments. Phenolic metabolites were absent in the apoplast and downregulated in the symplast, while proline exhibited contrasting levels in MYMIV-infected samples. Additionally, heightened aspartate levels were confined to the symplast. These findings provide insights into metabolites associated with stress and defense mechanisms triggered by MYMIV infection. In conclusion, our findings may help prevent an epidemic of YMD in Vigna species, and the study may contribute to enhancing disease management strategies in mungbean cultivation.
Prediction of Textured Journal Bearing Performance Characteristics implementing Mass Conserving Boundary Conditions using Progressive Mesh Densification Method
(2023) Rasool, Syed Nayab
Surface texturing is proven to be a feasible technique for enhancement of the performance characteristics of the hydrodynamic bearings. A considerable amount of numerical and experimental study is carried out on textured hydrodynamic bearings. The surface texturing onto the bearing surface can be done using different micro-fabrication techniques such as laser surface texturing (LST), chemical etching techniques, novel dressing techniques, Additive manufacturing, abrasive jet machining, photolithography, focused ion beam, micro-electric discharge machining, electrochemical texturing, ultrasonic machining, thermal implantation etc. The surface texture of regular geometries, either dimpled or protruded shapes, can be produced on the bearing surface with the above-mentioned manufacturing techniques
Analysis and Identification of Dynamic Transmission Error Parameters in a Geared Rotor Using Full Spectrum
(2023) Rao, Bhyri Rajeswara
Geared rotor bearing systems are widely used torque carrying components in most of the mechanical and electrical equipment in the automotive, aerospace and ship building industries. A dominant source of vibration in geared rotor systems are the gear mesh dynamic transmission error (TE) parameters. These include the static TE, the mesh stiffness and damping, and the gear runout. One needs to know additionally these dynamic parameters along with the gear macro-geometry (for examples, the number of teeth, pitch circle diameter, pressure angle, and tooth geometries), load and rotating speed, for the
vibration-based diagnosis of geared rotor power transmission units.
(The) Phonetics and Phonology of Tones in Mizo
(2023) Lalhminghlui, Wendy
This dissertation provides a comprehensive description of the tonal phonetics and phonology of Mizo, a Tibeto-Burman language. Previous studies have confirmed four lexical tones in Mizo, namely, high, low, rising, and falling. Since lexical tones can have different characteristics, this thesis attempts to characterize the four Mizo tones in terms of phonology and phonetics. The phonological analysis of the Mizo tones using the four distinct Mizo tones embedded in different contexts with certain word classes and morphological domains revealed that tones in Mizo could have tonal alterations. Specifically, the tones with prominent dynamic contours, such as falling and rising in Mizo, are more inclined towards tone alteration. The phonological tonal process called tone sandhi is attested in this dissertation, whereby a rising tone becomes a low tone when followed by a high or a falling tone. The investigation of rising tone sandhi domains provided evidence that the tonal context entirely triggers this phenomenon. Furthermore, the results of the production and perception tests of rising tone sandhi revealed that the derived low tone from rising tone sandhi is distinct from the canonical Mizo low tone, and the native speakers of Mizo were able to perceive the two tones categorically. Phonetic analysis of the Mizo tones using acoustic features such as fundamental frequency, duration, and dynamic nature in five contexts confirmed four lexical tones. This study also presents the gender differences in producing Mizo tones. The comparative analysis of the five contexts conveyed that tones produced in a more natural speaking style have smaller ranges of fundamental frequency and duration. Furthermore, the automatic classification of the tones in Mizo conducted using Quadratic Discriminant Analysis (QDA) and Random Forest (RF) revealed that the slope feature plays a crucial role in classifying the four Mizo tones. Besides the acoustic characteristics of the canonical tones in Mizo, this dissertation also provided the changes to the tone contours due to the effect of stop consonants and vowel types. The study of Mizo stop consonants revealed that the stops in Mizo conformed to the universal Voice Onset Time (VOT) patterns whereby the voiceless aspirated velar stop has the longest positive VOT, and the voiced unaspirated bilabial stop has the highest negative VOT. The analysis of the formant frequencies of Mizo vowels also substantiated that there are five distinct vowels in Mizo with long vowel counterparts, namely, /a, i, e, u, o/. Further investigation confirmed the significant interaction between Mizo tones and segments.