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Thapar Institute of Engineering & Technology (TuDR)

Welcome to Thapar Institute of Engineering & Technology Digital Repository (TuDR).

TuDR is the digital asset management system which integrates the intellectual output in the form of research articles, PhD theses, and M.Tech / M.E. theses. TuDR facilitates the sharing and exchange of intellectual output of the university.

TuDR supports the management of scholarly resources of enduring value to Thapar University. Faculty members, students, and research scholars use TuDR services to share their intellectual work with the global academic community.

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Recent Submissions

Photocatalytic Hydrogen Production from Biomass Under Solar Irradiation
(2026-09-18) Raina, Pragnaya; Pal, Bonamali
This study aimed at finding ways to harvest hydrogen as sustainable fuel from renewable source using clean and abundant solar energy. Sawdust, a renewable and waste material was used for H2 production, which categorises the harvested hydrogen as ‘green hydrogen’. Initial hydrothermal valorisation of sawdust yielded us cellulose, which was used as the sacrificial agent. Sacrificial agent was then photo-reformed to hydrogen using photocatalyst TiO2 photodeposited with Au, coated with rGO. TiO2, Au and rGO being non-toxic and environmentally friendly didn’t hamper the ‘green’ hydrogen production. TiO2, a semiconductor has band gap of approximately 3.2 eV, which renders it an effective photocatalyst. Nevertheless, its effectiveness is hindered by the rapid recombination of electron-hole pairs. To overcome this, Au of (1,3,5) wt. percentage was photo-deposited onto TiO2, as metal deposition enhances charge separation. Au also exhibits surface plasmon resonance (SPR), improving light absorption. Among the different loadings tested, 3% Au proved to be the most effective, increasing efficiency without obstructing active sites. Modification of metal loaded photocatalyst with rGO, which is conductive material with π conjugation, helps in further reduction in recombination of electron and holes, this increases the photocatalytic activity, with its best performing wt. % was 10% rGO out of 5, 10 & 12 wt. % rGO on 3% Au-TiO2. Furthermore, the use of biomass, sawdust as sacrificial agent is great aid for activity enhancement, as it is oxidised by photo-generated holes which reduces the recombination rate also increasing the quantum yield of photo-catalytically produced green H2. The research successfully illustrated biomass photo-reforming into green hydrogen, yield up to 296.12 mmol, as verified by gas chromatography.
Performance Analysis of Photonic Ring Resonator for Sensing Application
(2026-09-18) Geetika; Kaler, Rajinder Singh
The growing demand for high-speed communication systems, miniaturised optical components and advanced sensing platforms has accelerated the growth of photonic technologies that are emerging as a replacement for traditional electronic systems. As data traffic increases with advances in artificial intelligence and biomedical research, the limitations of conventional electronic systems, such as bandwidth constraints, response speed and high energy consumption, are becoming significant challenges. Therefore, the global research efforts are increasingly focused on photonic integrated circuits (PICs) that are capable of precise signal routing, effective wavelength control and high-performance sensing with low energy consumption. In this context, microring resonators (MRRs) have emerged as a crucial component. Their compact size, high Q factor and wavelength selectivity make them effective in high-speed data transmission and sensing. The work focuses on enhancing the performance of MRR systems used in optical filtering, sensing and switching. Initial investigations on basic MRR architectures, such as all-pass and add-drop configurations, exhibited that these are capable of performing wavelength-selective operations. Their compact design makes them well-suited for integration into photonic circuits. However, they have several limitations, such as limited bandwidth, reduced spectral selectivity, non-uniform passband responses and a trade-off between Q-factor and signal isolation, which limit their use for high-speed optical communication systems. To address these challenges, the present study investigates high-order MRRs designed to achieve flatter spectral responses, a wide free spectral range and improved signal separation for efficient filtering and switching. In addition, highly sensitive MRR based sensors are also presented, which can identify minor changes in the surrounding refractive index, highlighting their potential for biological sensing applications. Thus, the research aims to develop low-loss, reconfigurable and high-performance photonic devices for next-generation integrated optical systems. The work begins by exploring high-order optical filters based on serially coupled MRRs to support efficient on-chip photonic interconnects. Using the transfer matrix method and coupled-mode theory, multiple cascaded arrangements up to the seventh order are designed and analysed through the continued fraction method to achieve flat-top transmission characteristics, steep roll-off, and enhanced group delay. The inter-resonator coupling coefficients are optimised to achieve a maximally flat passband, leading to improved filter characteristics. The results showed that the designed high-order filters provide strong rejection of out-of-band signals and maintain a nearly constant free spectral range (FSR). The proposed design achieved an improved group delay of 7.457 ps at the optimised coupling coefficient, representing excellent spectral performance. The achieved box-shaped spectrum and strong out-of-band suppression prove that the proposed design is well-suited for communication networks and on-chip optical platforms. These characteristics provide a strong foundation for designing compact, low-loss and reconfigurable photonic integrated systems. Additionally, the work also explores applications in optical switching where MRR based structures are employed to implement switches for Optical Network-on-Chip (ONoC) architectures. These switches are designed to improve on-chip routing, reduced latency and allow for the control of optical signals with improved energy efficiency. Three different switch configurations, i.e. 1×2, 2×2 and CRIT-based 2×2 switch have been developed with a compact footprint. The 1×2 configuration provides efficient wavelength-selective routing exhibiting minimal insertion loss with a high extinction ratio, making it suitable for optical signal selection. The 2×2 design supports bar and cross states and offers flexible signal control with moderate performance trade-offs. The CRIT-based 2×2 switch further improves performance by achieving a narrow transmission bandwidth and reduced power consumption through coherent interference of coupled resonators. These results indicate that compact MRR based switches provide scalable, low-power and high-speed performance for future photonic interconnect applications. The work is further extended by applying ring resonators for sensing applications. In this, two sensor designs, i.e. a butterfly-shaped absorber employing elliptical ring resonators and a multi-ring graphene-based refractive index (RI) sensor are presented. The butterfly-shaped absorber uses three layers comprising a metallic ground plane, a dielectric substrate and a top resonant layer patterned in butterfly geometry. The near-perfect absorption and strong field confinement provides enhance sensitivity to refractive index variations in the surrounding medium. The coupling between electric and magnetic fields enhances resonance sharpness and increases the absorption efficiency, enabling precise detection of even minor analyte changes. After this, the graphene-based sensor integrates multiple ring resonators with a monolayer graphene to achieve tunable multi-band absorption. The tunability of graphene through changes in its chemical potential and relaxation time provides dynamic control on resonance frequency, resulting in a reconfigurable sensor suitable for multiple sensing applications. The coupling between multiple ring resonators enhances the sharpness of the resonance with a higher quality factor leading to enhanced sensitivity. The simulation results indicate red shifts in resonance frequencies with changes in the analyte refractive index, thereby highlighting the suitability of proposed design for biomedical sensing. This design enables multi-analyte detection, thus extending the role of MRRs beyond communication to precision sensing in the THz regime. Overall, this thesis integrates the progress in filtering, switching and sensing photonic design approach based on ring resonator architectures. Each design is supported by simulations and parametric performance analysis, with key parameters thoroughly evaluated and optimised. The progression from single-ring to multi-ring architectures demonstrates consistent improvements in bandwidth, tunability, and energy efficiency, while the proposed configurations exhibit high scalability and compatibility for integration into PICs. Beginning from fundamental optical filtering concepts, advancing towards optical switching, and extending into terahertz (THz) metamaterial and graphene-assisted sensing, the results confirm that optimised architectures can overcome the limitations of conventional devices, offering compact and high-performance solutions for all-optical communication and biosensing applications.
Overexpression and Purification of Arabidopsis thaliana HKT1;1 protein in yeast Pichia pastoris
(2026-09-18) Rishabh; Dutta, Debajyoti
Salinity is one of the most important abiotic stresses on about 20% of the world's irrigated areas. It is a serious issue that compromises world food production. Salt tolerance in plants depends on the regulation of ion homeostasis by membrane transporters AtHKT1;1 of Arabidopsis thaliana is one such crucial transporter. It helps in the retrieval of Na⁺ from the xylem sap to safeguard photosynthetic tissues. AtHKT1;1 has been physiologically validated in several organisms, but there is no report of its functionality in Pichia pastoris, a scalable platform that is ideal for biochemical and structural studies. The purpose of this thesis was to heterologouslyexpress, purify and detect AtHKT1;1 in Pichia pastoris GS115. Transformed cells with the pPICZ-A‑athkt1;1construct was grown in BMGY medium, induced with methanol for 72 h and harvested. Two parallel membrane isolation protocols were tested: direct Sonication followed by solubilization and Zymolyase mediated spheroplast formation followedby Sonication and solubilization. His‑tagged protein was prepared using Ni‑NTA affinity column and eluted with 300 mM imidazole. The level of protein expression and purification was tracked by SDS-PAGE and Western blotting with anti‑His and anti‑eGFP antibodies. Elution fractions from both isolation techniques showed a band corresponding to the expected molecular weight on Coomassie-stained gels and Western blots, and the isolation and purification of AtHKT1;1 in Pichia pastoris were successful. The purified protein was kept at –80 °C for future studies. This work represents the first functional validation of AtHKT1;1 produced in P. pastoris and includes a reproducible pipeline for production of AtHKT1;1 that enables further analysis, including interactome mapping and structural characterization.
Study of microstructure and magnetic properties in transition metal-based High Entropy Alloys
(2026-09-17) Piplani , Dushyant; Kashyap, Sanjay
Alloys have played a major role in the development of human civilization. Earlier, they were made with a combination of around two metals. In this work High Entropy Alloys (HEAs) were studied which are the combination of five or more than five elements. Alloy-1 (Fe0.25Co0.25Ni0.25Cr0.25) has four elements, which act as a base alloy. It satisfies the definition of a Medium Entropy Alloy (MEA) with 𝛥𝑆mix around 1.3 R. Mn, Ge, and Si were added, which formed alloy-2 (Fe0.2Ni0.2Cr0.2Co0.11Mn0.11Ge0.9Si0.9). This alloy satisfies the definition of High Entropy Alloys with 𝛥𝑆mix ~ 1.8 R. It was found that alloy-1 shows a dominant FCC phase. Two peaks were undetermined in the XRD of alloy-1. Still, the FCC phase is dominant. It was further found that the BCC phase in alloy-2 is the dominant phase, with one undetermined peak, which may be there due to the formation of the intermetallic (IM). SEM micrographs show the columnar grains in alloy-1 and dendritic formation in alloy-2. From the EDS data, it was found that all the elements in alloy-1 were found to be equally distributed, forming a solid solution. In alloy-2, segregation of Si was found to be in and around the interdendritic region. The hardness of the system drastically increased from around 130 HV0.5 in alloy-1 to around 640 HV0.5 in alloy-2. It was attributed to the presence of Si and Ge, as they have different atomic sizes compared to other elements. At last, the magnetic properties of both systems were studied with the help of VSM. It was found that alloy-1 showed paramagnetic properties at room temperature, and alloy-2 showed soft-ferromagnetic properties at room temperature.
Phycoremediation of wastewater by diatoms and microalgae
(2026-09-17) Kour, Sanjam; Goyal , Dinesh
Native microalgae and diatoms were isolated from wastewater collected from Jayanti Ki Rao (JKR) Channel, Kharar. Morphological characterisation showed dominant diatom species Navicula sp. and Nitzschia sp. These diatoms along with previously isolated microalgae Chlorella sp. (DGNH-3) and Scenedesmus sp. (DGNH-4), were employed to evaluate their phycoremediation potential by treatment of effluent from Sewage Treatment Plant (STP) of Thapar Technology Campus, Patiala. The performance of individual cultures and mixed consortia was assessed based on dissolved oxygen enhancement, biomass productivity, nutrient removal, and improvement of wastewater quality. Wastewater treatment significantly improved water quality parameters. Dissolved oxygen (DO) increased from 2.34 ± 0.01 mg/L to 10.4 ± 0.01 mg/L in the control (77.5% increase), 10.09 ± 0.01 mg/L in the diatom treatment (76.81% increase), and 11.5 ± 0.01 mg/L in the algal–diatom consortium (79.65% increase). Biological oxygen demand (BOD) decreased from 190 ± 0.02 mg/L to 41 ± 0.02 mg/L in the control (78.42% reduction efficiency), 23 ± 0.02 mg/L in the diatom treatment (87.89% reduction efficiency), and 20 ± 0.02 mg/L in the consortium (89.47% reduction efficiency). Total dissolved solids (TDS) were reduced from 1.30 ± 0.03 ppm to 0.757± 0.03 ppm (41.77% reduction), 0.786 ± 0.01 ppm (39.54% reduction), and 0.615 ± 0.03 (39.54% reduction) ppm in the control, diatom, and consortium treatments, respectively. Similarly, conductivity declined from 1658 ± 0.02 μS/cm to 1193 ± 0.04 μS/cm (control) (28.04% reduction), 1173± 0.02 μS/cm (diatoms) (29.25% reduction), and 1163 ± 0.02 μS/cm (consortium) (29.86% reduction), demonstrating that the algal–diatom consortium achieved the highest overall remediation efficiency. Biomass productivity demonstrated effectiveness of microalgae in simultaneous treatment of wastewater and biomass generation. These findings overall confirm that microalgal–diatom consortia are an efficient environmentally sustainable solution for wastewater cleanup.