About

Avijit Singh is a third-year Ph.D. candidate in the Department of History at The Ohio State University, with a focus on South Asian studies, childhood history, social history, gender and labour studies, and British imperial history. His research investigates how orphans were defined and cared for by the colonial state, religious organizations, and other non-state actors, particularly during moments of crisis such as famines and epidemics in 19th century India. His work explores the politics of orphan care through the lenses of gender, caste, and labour, aiming to problematize colonial development and welfare by examining the complexities of social and political history.

Research topics

• Computer science
• Materials science
• Optoelectronics
• Electrical engineering
• Parallel computing

Selected publications

• Predictive Modeling and Optimization of Microalgae Chlorella vulgaris Biodiesel Production: Assessing the Performance of a Raw Biogas-Powered Diesel Engine with Diethyl Ether Blended Biodiesel

  Journal of Environmental Informatics · 2025-01-01 · 13 citations

  articleOpen accessSenior author

  Biodiesel production has drawn significant interest due to its potential as a renewable and environmentally favorable alternative to conventional diesel fuel. This study focuses on the prediction and optimization of biodiesel synthesis from Chlorella vulgaris microalgae oil using response surface methodology (RSM) and genetic algorithm (GA). The transesterification process factors, including molar ratio, catalyst concentration, reaction temperature, reaction time, and stirring speed, are explored using a Box-Behnken Design (BBD). The GA proved to be the optimal parameter combination for achieving a high biodiesel yield. Under the optimized conditions of molar ratio of 6.77:1, catalyst concentration of 1.38 wt%, reaction temperature of 65 °C, reaction time of 90 min, and stirring speed of 574 rpm, the biodiesel yield reached 98.38% (wt%). Experimental validation confirms the accuracy of the predicted results. This study also investigates the efficient use of produced biodiesel with diethyl ether as an additive and diesel blend in a dual-fuel diesel engine mode by varying the biogas mass flow rate (6, 8, and 10 L/min). Test blends of biodiesel/diesel/diethyl ether as pilot fuel and biogas as the primary fuel demonstrate satisfactory engine performance and reduced NOx and smoke emissions compared to baseline diesel. However, carbon monoxide (CO) and hydrocarbon (HC) emissions increase. Among the tested blends, B20DEE10Bio (10) exhibited diesel-like engine performance, resulting in a 3.47% increase in brake thermal efficiency (BTE) and a 4.17% decrease in brake-specific fuel consumption (BSFC). While NOx and smoke emissions decreased by 30.78 and 54.6%, CO and HC emissions increased by 41.27 and 37.3%, respectively, compared to baseline diesel. This research contributes to the optimization of biodiesel production and its utilization in sustainable energy systems, offering a promising pathway towards reducing environmental impacts and achieving energy security.

  PublisherOA PDFDOI

• Optimising Ex-Vivo Hand Imaging at Ultra-High FIeld (7T)

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  article

  Motivation: Ex-vivo MRI of hand specimens at ultra high field enables unprecedented, non-destructive, high resolution imaging not possible in-vivo. However, it poses a challenge requiring robust methodology and optimisation of vendor sequences that have not previously been reported. Goal(s): Our goal was to determine preparation and acquisition methods for optimised spatial resolution and contrast. Approach: Systematic testing of parameters for PD SPACE was conducted and evaluated with SNR and CNR calculations. Combinations of coils and specimen preparation methods were trialled. Results: We demonstrate optimised methodology and sequence parameter choices enabling high-resolution imaging with superior contrast in ex-vivo hand tissue. Impact: This work provides preparation methods and sequence parameters for imaging of ex-vivo hand specimens at UHF (7T) for high contrast and spatial resolution. This enables improved visualisation of anatomical detail and may be translated to other anatomical regions.

  PublisherDOI

• Simulation study of leakage current in junction less field effect transistor

  AIP conference proceedings · 2024-01-01

  article
  PublisherDOI

• InAs Raised Buried Oxide SOI-TFET with N-type Si_1-xGe_x Pocket for Low-Power Applications

  BENTHAM SCIENCE PUBLISHERS eBooks · 2024-06-26

  book-chapter1st authorCorresponding

  In this chapter, we studied the device-level performance based on electrostatic parameters of a source pocket engineered raised buried oxide (RBOX) SOI tunnel field-effect transistor (SP-RBOX-SOITFET). Using Si1-xGex pockets between the channel and the source, steep subthreshold swing transistors can be obtained. In the pocket, a narrow n+ region is formed by a tunneling junction between the p+ region of the source. In order to reduce subthreshold swing, the tunneling width must be narrowed, and the lateral electric field must be increased. So, the studied structure can be used to design the dielectric modulated biomolecule biosensors for IOTs applications. Simulation analyses of the proposed work has been conducted using the Silvaco ATLAS TCAD tool.<br>

  PublisherDOI

• Dielectric modulated TFET on SELBOX substrate as a label-free biosensor applications: analytical modeling study and sensitivity analysis

  Physica Scripta · 2024-09-19 · 5 citations

  article1st authorCorresponding

  Abstract The manuscript proposes a ferroelectric heterojunction TFET (BG-FE-HJ-STFET) on SELBOX substrates with a back gate to create an ultra-sensitive label-free biosensor with dielectric modulation for the detection of neutral and charged biomolecules. Within the proposed device, four cavities have been carved out for the biomolecules’ immobilization under the front and rear gate dielectrics. By using a ferroelectric (FE) material as a gate stack, the low gate voltage is increased to be more effective by causing a negative capacitance phenomenon. The response of the proposed biosensor to four impartial biomolecules with different dielectric constants: protein ( k = 8), biotin ( k = 2.63), 3-Aminopropyl-triethoxysilane (APTES) ( k = 3.57), and streptavidin ( k = 0.1) has been investigated. Deoxyribonucleic acid (DNA), a charged biomolecule, is also examined for the dielectric constant of k = 6 concerning both charge (negative and positive) densities. The device is simulated with the commercially available SILVACO ATLAS TM TCAD tool. The performance analysis relies on several figures of merit (FOMs) such as DC/RF and sensitivity (including drain current, I ON /I OFF ratio, and subthreshold swing) for both neutral and charged biomolecules. The optimized cavity structure demonstrates a notable sensitivity in drain current (2.7 × 10 8 ) and a significant I ON /I OFF sensitivity (1.42 × 10 11 ). One of the main problems with current biosensors is the difficulty and expense of production in the nanoscale realm.

  PublisherDOI

• A New Approach to Design of Cost-Efficient Reversible Quantum Dual-Full Adder and Subtractor

  International Journal of Mathematical Engineering and Management Sciences · 2024-02-21 · 2 citations

  articleOpen access

  This paper proposed the design and development of reversible cost-efficient innovative quantum dual-full adder and subtractor or QD-FAS circuit using quantum gate. The proposed circuit can be used as full adder and full subtractor simultaneously, which is designed using double Peres gate or DPG and Feynman gate or FG. The quantum cost, garbage output and constant input of the QD-FAS is 8, 1 and 1. Which is better w.r.t previously reported work. The QD-FAS circuit, as proposed, includes shared sum and difference terminals, as well as a carry-out and a borrow output terminal. Notably, this innovation showcases a remarkable 27.27% reduction in quantum cost. The improvement in garbage output is even more striking, showing a 50% enhancement. When assessing the overall advancement in quantum cost, it falls within the range of 27.27% to 66.66%. To confirm the viability of this design, extensive testing is carried out using the IBM Qiskit simulator. This design holds significant importance in a variety of applications, including quantum computing, cryptography, and the realm of reversible Arithmetic Logic Units (ALU).

  PublisherOA PDFDOI

• A Phantom-Based Experimental Study of the Bioimpedance Monitoring Techniques

  2024-06-20

  book-chapter

  A recently established new technique is electrical impedance tomography (EIT), which relates as per the interior impedance distribution for a subject (medical or nonmedical applications) measured from different locations was reconstructed into an image. The electrical impedance methodology consisted of topology of the electrodes configrations and that are attached with the subject of the circumference. The current source and measuring voltage position are defined through the proposed approach. A constant current (mill ampere current with kHz frequency) is passed into the boundary of an object through some electrodes pairing. The output voltages are measured from the periphery of the conductive object by another pair of electrodes, and the data was fed into a computer for computation. The image reconstruction of the cross-sectional image of resistivity is based on the finite element method and EIDORs toolkit on MatLab. The proposed system is validated on different phantoms for biomedical as well as industrial applications. It is more energy effiecnt and innovation for engineering research as well as medical-based application.

  PublisherDOI

• DC and RF Performance Optimization of Source Pocket Designed Hybrid-Dielectric Vertical Nanowire Tunnel-FET: Low Power Perspective

  ECS Journal of Solid State Science and Technology · 2024-11-21 · 3 citations

  article

  This article addresses a new source pocket designed hybrid-dielectric vertical nanowire tunnel-FET (SP-HD-VNW-TFET). The existence of a source pocket at the source and channel boundary is shown such that the potential barrier at the tunnel-junction is minimized which causes ON current to rise. This article studied a comparison between a SP-HD-VNW-TFET device and source pocket vertical nanowire tunnel field effect transistor (SP-VNW_TFET). Using a hetero/hybrid-dielectric material boosts the electric field, resulting in higher tunneling current (1.72 × 10 −6 A μm −1 ). The device has undergone detailed investigation of both DC and AC characteristics like On-current, Off-current, I ON /I OFF , Subthreshold-swing, V T , g m , f T , GWB, and TFP. Source Pocket engineering and Hybrid dielectric inclusion increase device properties, including on-current and subthreshold swing (SS). The device’s electrical properties have been evaluated and compared using the Sentaurus TCAD Tool.

  PublisherDOI

• GaAs-on-insulator based vertical heterojunction tunnel FET: proposal and analysis for VLSI circuit applications

  Physica Scripta · 2024-07-12 · 4 citations

  article

  Abstract This work analyses the Gallium Arsenide (GaAs)-on-insulator based vertical heterojunction tunnel FET with Gallium Antimonide (GaSb) as source material and GaAs as channel/drain material (GaSb/GaAs VTFET) to enhance the performance of the device and is compared with the Silicon-based VTFET. Silvaco Atlas TCAD tool is employed to perform numerical calculations. Tentative fabrication process flow of GaSb/GaAs VTFET is presented. GaSb is a low bandgap material that enhances the tunneling of charge carriers at source-channel heterojunction. GaSb/GaAs VTFET device outperforms Si-based VTFET in terms of electrical performance metrics such as ON-state current (I ON ), and I ON /I OFF increases by a factor of 11 and 270 respectively; whereas OFF-state current (I OFF ), subthreshold swing (SS), threshold voltage (V T ) and drain-induced barrier lowering (DIBL) reduce by 95.98%, 39.36%, 17.14% and 29.17% respectively. Further, analog/RF and linearity/distortion performance analysis is carried out. GaSb/GaAs VTFET has improved analog/RF performances in terms of cut-off frequency (f T ), gain-bandwidth product (GBP), transit time ( τ ), device efficiency (DE), transconductance frequency product (TFP) and suppressed distortions in compare to Si-based VTFET. Finally, GaSb/GaAs VTFET is evaluated for process variations and designing digital inverter and common source amplifier circuits. The Look-up-table (LUT) based Verilog-A model within the CADENCE tool has been employed to scrutinize the transient responses of inverter and common source amplifier circuits. Unity gain frequency and 3-dB bandwidth obtained for GaSb/GaAs VTFET amplifier are 15 GHz and 5.97 GHz. Therefore, this work presents GaSb/GaAs VTFET’s strong candidature for analog and digital VLSI circuit designing.

  PublisherDOI

• Simulation Analysis of High-k Dielectric Junction less FET for Reduction of Subthreshold Leakage Current

  2023-03-17 · 3 citations

  article

  With the purpose of reduction of the subthreshold leakage current, high-k dielectric material is used, as this work demonstrates. The because of high leakage current and a sharp rise in tunneling, SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> conventional MOSFET feature sizes have reached their physical limits, where reducing the oxide thickness below 2nm become not possible. Because of this, it is challenging to reduce MOSFET size and increase performance at the same time. Transistor parameters like oxide thickness channel length, and channel width can be altered instead of the transistor’s size being shrunk. The device’s performance could be impacted by these, though. Therefore, the impact of substituting another high permittivity material for SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> has been studied. SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> , Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> , HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> , Ta <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> , and La <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> were among the materials employed in the analysis. SILVACO TCAD simulation was used to test the characteristic of subthreshold leakage current.

  PublisherDOI

Frequent coauthors

• Satyabrata Jit

  Banaras Hindu University

  19 shared

• Manas Ranjan Tripathy

  Indian Institute of Technology BHU

  17 shared

• Bineet Kaur

  Chitkara University

  16 shared

• Susmita Biswas

  Haldia Institute of Technology

  16 shared

• Prince Kumar Singh

  Agricultural Institute

  16 shared

• Parna Kundu

  National Institute of Technology Durgapur

  16 shared

• Heranmoy Maity

  16 shared

• Aritra Bhowmik

  16 shared