2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA), Mar 1, 2018
Free Space Optics (FSO) is that branch of the optical communication which provide better bandwidt... more Free Space Optics (FSO) is that branch of the optical communication which provide better bandwidth requirement, highly secure system and ease in the installation of communication system. No need of any kind of permit for FSO use and also provides better data rate. In topographical area like hill station and other high altitude area where the optical cable based communication system is quite difficult we can use FSO based ROF-WDM system. In this paper, analysis of FSO based ROF-WDM system is done under different advance intensity modulation techniques and effect of the atmospheric condition on the system is also studied.
A WDM system forms the backbone of Optical Networks. It increases the transmission capacity by re... more A WDM system forms the backbone of Optical Networks. It increases the transmission capacity by reusing existing fibre cables. WDM combines cost-effectiveness with scalability. In this paper, we have analysed the performance of the 4 channel WDM system. The configuration consist of 4 input channels transmitter, combiner, splitter, fiber channel(amplifier and fiber cables), optical filter, electric filter, photodiode, electrical scope. The length used for Fiber Channel was 100km. Simulation of proposed model was carried out and results were analyzed. The analysis of simulation is done on the basis of Q-factor and BER.
2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA), 2018
Free Space Optics (FSO) is that branch of the optical communication which provide better bandwidt... more Free Space Optics (FSO) is that branch of the optical communication which provide better bandwidth requirement, highly secure system and ease in the installation of communication system. No need of any kind of permit for FSO use and also provides better data rate. In topographical area like hill station and other high altitude area where the optical cable based communication system is quite difficult we can use FSO based ROF-WDM system. In this paper, analysis of FSO based ROF-WDM system is done under different advance intensity modulation techniques and effect of the atmospheric condition on the system is also studied.
and a friend during the course of the study. I really appreciate him providing me the ground to t... more and a friend during the course of the study. I really appreciate him providing me the ground to think and execute with his unfailing patience and consistent motivation, this wouldn't have been possible without his support. His unprecedented vision and faith kept me motivated through my journey as a Ph.D. student. I would also like to thank Dr. Sundar V. Atre, who was always there to provide his guidance and support, and I cherish every discussion we had over the past years. He has been a great role model with exceptional leadership and visionary. With Dr. Kunal H. Kate and Dr. Sundar V. Atre have both contributed to my growth as an individual and as a researcher by setting great example of professionalism. I would extend my sincere gratitude and thanks to Dr. Vamsi K. Balla who has been a very crucial person in providing guidance and help during his 1-year visit to the University of Louisville and continues to support. I enjoyed all discussions and learning received from his experience. Also, I would thank Dr. Azim Gokce for sharing his expertise, guidance and friendship. I also want to thank my committee members, Dr. Thomas A. Berfield and Dr. Jagannadh Satyavolu for taking time out of their busy schedule and providing constructive criticism for my research. I would like to extend my gratitude to Dr. Thomas A. Berfield to allow me to use his laboratory facility at times and providing necessary advice. I would like to v thank Dr. Jacek Jasinski to provide me with the access to facilities at the Conn Center, and answering all of my questions. I take the opportunity to thank each member of the NASA FABLAB team, Lawrence Hubner, Curtis Hill, Tracie Prater, Christopher Roberts, and others, for giving me the opportunity to work with them on a great project and hold insightful discussions in the review meetings. A very special thanks to Techshot team members Andy Kurk, Brian Gettler, Stephen Tuma, and others for the unparallel trust in my work and helping with all necessary furnace runs and other required testing. I would like to thank Stefan Joens and Bryan Sherman at DSH Technologies for providing insight and help in performing initial sintering experiments. I would also like to thank Andy Shives at Praxair Surface Technologies for meeting Ti-6Al-4V powder requirements. I would also thank Jim Adams from the Material Powder Industries Federation (MPIF) for his generosity and support that allowed me to present at the international conferences. This definitely has contributed to my professional growth and network. I would also like to thank Dr. Randall German for being a great support all the time, providing guidance and advise on the Ti-6Al-4V processing and challenges.
Polarity Classification over Twitter offers different organizations a fast and effective way to m... more Polarity Classification over Twitter offers different organizations a fast and effective way to monitor the feelings/emotions of general public towards their brand, business, politicians etc. A wide range of features for training polarity classifiers for Twitter datasets have been researched in recent years with varying results. In this paper, we introduce a novel approach for automatically classifying and adding semantics as additional features the polarity of Twitter messages. These messages are classified as positive or negative or neutral with respect to a query term. The paper focuses on addressing polarity classification for product features in product reviews by building semantic association between product features and polarity words. The results show that our method is encouraging. Keywords— Corpus, tweet, analysis, sentiment, polarity, twitter
IT world is changing. Evolution of cloud computing in recent past has brought drastic change in e... more IT world is changing. Evolution of cloud computing in recent past has brought drastic change in era of IT field. Major advantage of cloud computing is that the hardware need not to be upgraded as Cloud Services provides everything of demand basis. Consuming electricity is the best example by which cloud computing can be explained, just pay for whatever you used. In this paper, we present a comparative study of leading cloud providers such as Amazon Cloud Services, Rackspace powered by OpenStack and other open source Cloud providers. Further discussing about how to implement OpenStack or just trying out by Devstack and Trystack just for testing purpose and at last covering releases and recent work going on in OpenStack. The aim of this paper is to show importance of OpenStack as a Cloud provider and how to get started with OpenStack.
This paper presents metal-fused filament fabrication (MF 3) for manufacturing Ti-6Al-4V parts by ... more This paper presents metal-fused filament fabrication (MF 3) for manufacturing Ti-6Al-4V parts by 3D printing of green parts followed by debinding and sintering to obtain mechanical properties comparable to metal injection-molded (MIM) specimens. The current work discusses critical material and process aspects of the MF 3 process that currently limits it from effective defect-free translation from 3D printed to sintering. We show successfully produced bound filament with 59 vol% of Ti-6Al-4V powder mixed with a polymeric binder system to print parts using MF 3. The feedstock and filaments showed uniform powder dispersion and acceptable flowability necessary for consistent extrusion during MF 3 printing, leading to defect-free parts. The green part density was 98.5 ± 0.6% relative to the density of the 59 vol% Ti-6Al-4V feedstock that resulted in successful debinding without slumping, no warpage, and layer delamination of the MF 3 parts. A two-step debinding combining solvent and thermal extraction of polymer binder followed by sintering in partial vacuum resulted in almost isotropic shrinkage of ~ 14% in all directions. The sintered density of these parts was 94.2 ± 0.1%. The mechanical properties of the present MF 3 processed Ti-6Al-4V alloy parts represent UTS of 875 ± 15 MPa and elongation of 17 ± 3%, which being 1.7% higher in UTS and 17.5% higher in elongation when compared to literature data for metal injection-molded parts.
Spectral amplitude coding optical code division multiple access (SAC-OCDMA) is one of the most im... more Spectral amplitude coding optical code division multiple access (SAC-OCDMA) is one of the most important multiplexing schemes of OCDMA that has turned out to be a stimulating investigating area in optical communication due to its increased privacy, network capacity and its flexibility in allocating the channels and asynchronous environment. On the other hand, Inter-satellite optical wireless communication (IsOWC) which is a favorable area of research in optical communication is useful for bursty transmissions and long-distance communications. In this paper, we have designed a hybrid SAC-OCDMA system through IsOWC channel using ZCC code for advanced intensity modulation formats (CSRZ, Db, and AMI). The investigation is done for four users at a bit rate of 40(4×10) Gb/s using a direct detection technique. Further, on comparing the proposed system using advanced intensity modulation formats, the result shows that system using CSRZ format is better in terms of BER, Q-factor, SNR and the...
Abstract This paper aims to break the current material-process-property tradeoffs in metal fused ... more Abstract This paper aims to break the current material-process-property tradeoffs in metal fused filament fabrication (MF3) to effectively fabricate Ti-6Al-4V alloy specimens beyond 90% relative density without any post-processing with consistent mechanical properties and microstructure, which are critical for aerospace and medical applications. Existing knowledge gaps in MF3 3D printing fail to address how properties scale from the filament processing stage to green part printing to sintering and what contributing factors cause significant deviation in mechanical properties in samples having the same sintered densities. To tackle these gaps, this work holistically investigates four key aspects specifically for MF3 of Ti-6Al-4V to address a) influence of filament extrusion conditions on filament density variance and diameter control, b) use of the design of experiments to identify factors influencing MF3 3D printed green sample density and dimensions, c) identifying sintering time and temperature conditions that yield densities beyond 90% and mechanical properties close to literature and d) how powder attributes (size and interstitial concentrations) and its effect on sintered density and mechanical properties for MF3 3D printed samples are discussed.
Journal of Materials Engineering and Performance, 2021
Building end-use functional metal parts by metal fused filament fabrication (MF 3) is an emerging... more Building end-use functional metal parts by metal fused filament fabrication (MF 3) is an emerging topic in additive manufacturing. MF 3 involves extrusion of polymer filaments that are highly filled with metal powder to print three-dimensional parts, followed by debinding and sintering to eliminate the polymer binder and get a fully dense metal part, respectively. Material properties, part design and processing conditions have a significant influence on the quality of MF 3 printed parts. Part distortion and dimensional variations are significant quality challenges that hinder the acceptance of printed parts in potential functional applications. Trial-and-error experiments to find the best conditions are commonly used for defect avoidance, though they are time-consuming and expensive. Hence, computational simulation and design solutions are required for MF 3 to enable a virtual analysis of the process outcome and reduce dependency on experimental methods. This paper investigates the applicability of a thermo-mechanical model for finite element simulation of the MF 3 printing process. The quantitative influence of material properties on MF 3 printed part quality was estimated using a simulation platform. The simulation results of two materials, a Ti-6Al-4V filled polymer and an unfilled ABS copolymer, were compared to experiments. It was determined that the unfilled polymer showed greater shrinkage and warpage than the Ti-6Al-4V filled polymer in simulations and experiments. Further, the trend in the distribution of warpage was consistent between experiments and simulation results for both materials. Finally, warpage compensation algorithms showed improvement in dimensional control for both materials in simulations and were consistent with experimental results.
Physica E: Low-dimensional Systems and Nanostructures, 2021
Abstract In this study, a backend gate GFET based sensor for the detection of COVID-19 via volati... more Abstract In this study, a backend gate GFET based sensor for the detection of COVID-19 via volatile organic compound biomarkers is designed and simulated. Graphene as the channel of the device is used as an adsorbing site for a biomarker, ethyl butyrate and the effect of the adsorption on the transport characteristics of the device is used as a sensing parameter. Functionalization of graphene with Platinum ameliorates the enticement between the biomarker and the host material calculated via adsorption energy. Density Functional Theory (DFT) is used to calculate the electronic and surface properties of the channel of the device, with and without adsorption of the biomarker. The calculated characteristic properties of the channel are used to figure out the transport properties of the device through COMSOL Multiphysics. Results show that adsorption of the biomarker on the functionalized graphene changes the dynamics of the charge carriers (via electronic properties) and results in variation in the transport properties of the device after adsorption of biomarker, making the device compatible for detection of COVID-19.
In this work, we have designed and simulated a graphene field effect transistor (GFET) with the p... more In this work, we have designed and simulated a graphene field effect transistor (GFET) with the purpose of developing a sensitive biosensor for methanethiol, a biomarker for bacterial infections. The surface of a graphene layer is functionalized by manipulation of its surface structure and is used as the channel of the GFET. Two methods, doping the crystal structure of graphene and decorating the surface by transition metals (TMs), are utilized to change the electrical properties of the graphene layers to make them suitable as a channel of the GFET. The techniques also change the surface chemistry of the graphene, enhancing its adsorption characteristics and making binding between graphene and biomarker possible. All the physical parameters are calculated for various variants of graphene in the absence and presence of the biomarker using counterpoise energy-corrected density functional theory (DFT). The device was modelled using COMSOL Multiphysics. Our studies show that the sensiti...
2021 IEEE 21st International Conference on Nanotechnology (NANO), 2021
In this study, we probe the surface engineered (vacancy and Stone Wales defective) hydrogen passi... more In this study, we probe the surface engineered (vacancy and Stone Wales defective) hydrogen passivated armchair graphene nanoribbon with a width of 7 atoms as a biosensing material to detect methanethiol biomarkers. Induction of defects results in the decrement of the bandgap by the formation of the trapping states. After geometry optimisation, it is found that only vacancy induced armchair graphene nanoribbon can form strong binding with the biomarker, whereas Stone Wales defect induced armchair graphene nanoribbon show disassociation with the biomarker by having positive adsorption energy. Using density functional theory, the electronic properties of a vacancy-induced armchair graphene nanoribbon with and without adsorption of methanethiol are calculated, showing that methanethiol adsorption leads to increment in the bandgap of the host material by eliminating the trapping states. The work function and electron affinity change after adsorption. As there are significant changes in the electronic properties, vacancy induced armchair graphene nanoribbon show high sensing capabilities toward methanethiol biomarkers.
Density functional theory-based first-principles investigation is performed on pristine and mono ... more Density functional theory-based first-principles investigation is performed on pristine and mono vacancy induced GaAs nanoribbons to detect the presence of three volatile organic compounds (VOCs), aniline, isoprene and o-toluidine, which will aid in sensing lung cancer. The study has shown that pristine nanoribbon senses all three analytes. For the pristine structure, we observe decent adsorbing parameters and the bandgap widens after the adsorption of analytes. However, the introduction of the carrier traps induced by defect causes deep energy wells that vary the electrical properties as indicated in the bandgap analysis of GaAs, wherein adsorption of aniline and o-toluidine reduces the bandgap to 0 eV, making the structure highly conductive in nature. The adsorption energies of defect-induced nanoribbon are more as compared with the pristine counterpart. Nonetheless, the introduction of defects has improved the sensitivity further.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
In order to achieve large capacity inter-satellite communication, optical wireless communication ... more In order to achieve large capacity inter-satellite communication, optical wireless communication (OWC) is emerging as a promising area of research amongst the academic and research groups. While radio over fiber (ROF) and advanced modulation technique is considered to be a key enabling technology in the development of OWC based access networks for high-speed data transmission. This paper has proposed a novel ROF based system model using OWC for long haul high data rate applications. This system is designed using differential quadrature phase shift keying (DQPSK) through inter-satellite optical wireless communication (IsOWC) channel. The verification of the performance is performed at bit rates of 100 and 200 Gbps over a space distance range up to 1000 to 50000 km under different transmitted power. The simulative investigation has been carried out in terms of important parameters like BER, Q-factor and eye diagrams.
2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA), Mar 1, 2018
Free Space Optics (FSO) is that branch of the optical communication which provide better bandwidt... more Free Space Optics (FSO) is that branch of the optical communication which provide better bandwidth requirement, highly secure system and ease in the installation of communication system. No need of any kind of permit for FSO use and also provides better data rate. In topographical area like hill station and other high altitude area where the optical cable based communication system is quite difficult we can use FSO based ROF-WDM system. In this paper, analysis of FSO based ROF-WDM system is done under different advance intensity modulation techniques and effect of the atmospheric condition on the system is also studied.
A WDM system forms the backbone of Optical Networks. It increases the transmission capacity by re... more A WDM system forms the backbone of Optical Networks. It increases the transmission capacity by reusing existing fibre cables. WDM combines cost-effectiveness with scalability. In this paper, we have analysed the performance of the 4 channel WDM system. The configuration consist of 4 input channels transmitter, combiner, splitter, fiber channel(amplifier and fiber cables), optical filter, electric filter, photodiode, electrical scope. The length used for Fiber Channel was 100km. Simulation of proposed model was carried out and results were analyzed. The analysis of simulation is done on the basis of Q-factor and BER.
2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA), 2018
Free Space Optics (FSO) is that branch of the optical communication which provide better bandwidt... more Free Space Optics (FSO) is that branch of the optical communication which provide better bandwidth requirement, highly secure system and ease in the installation of communication system. No need of any kind of permit for FSO use and also provides better data rate. In topographical area like hill station and other high altitude area where the optical cable based communication system is quite difficult we can use FSO based ROF-WDM system. In this paper, analysis of FSO based ROF-WDM system is done under different advance intensity modulation techniques and effect of the atmospheric condition on the system is also studied.
and a friend during the course of the study. I really appreciate him providing me the ground to t... more and a friend during the course of the study. I really appreciate him providing me the ground to think and execute with his unfailing patience and consistent motivation, this wouldn't have been possible without his support. His unprecedented vision and faith kept me motivated through my journey as a Ph.D. student. I would also like to thank Dr. Sundar V. Atre, who was always there to provide his guidance and support, and I cherish every discussion we had over the past years. He has been a great role model with exceptional leadership and visionary. With Dr. Kunal H. Kate and Dr. Sundar V. Atre have both contributed to my growth as an individual and as a researcher by setting great example of professionalism. I would extend my sincere gratitude and thanks to Dr. Vamsi K. Balla who has been a very crucial person in providing guidance and help during his 1-year visit to the University of Louisville and continues to support. I enjoyed all discussions and learning received from his experience. Also, I would thank Dr. Azim Gokce for sharing his expertise, guidance and friendship. I also want to thank my committee members, Dr. Thomas A. Berfield and Dr. Jagannadh Satyavolu for taking time out of their busy schedule and providing constructive criticism for my research. I would like to extend my gratitude to Dr. Thomas A. Berfield to allow me to use his laboratory facility at times and providing necessary advice. I would like to v thank Dr. Jacek Jasinski to provide me with the access to facilities at the Conn Center, and answering all of my questions. I take the opportunity to thank each member of the NASA FABLAB team, Lawrence Hubner, Curtis Hill, Tracie Prater, Christopher Roberts, and others, for giving me the opportunity to work with them on a great project and hold insightful discussions in the review meetings. A very special thanks to Techshot team members Andy Kurk, Brian Gettler, Stephen Tuma, and others for the unparallel trust in my work and helping with all necessary furnace runs and other required testing. I would like to thank Stefan Joens and Bryan Sherman at DSH Technologies for providing insight and help in performing initial sintering experiments. I would also like to thank Andy Shives at Praxair Surface Technologies for meeting Ti-6Al-4V powder requirements. I would also thank Jim Adams from the Material Powder Industries Federation (MPIF) for his generosity and support that allowed me to present at the international conferences. This definitely has contributed to my professional growth and network. I would also like to thank Dr. Randall German for being a great support all the time, providing guidance and advise on the Ti-6Al-4V processing and challenges.
Polarity Classification over Twitter offers different organizations a fast and effective way to m... more Polarity Classification over Twitter offers different organizations a fast and effective way to monitor the feelings/emotions of general public towards their brand, business, politicians etc. A wide range of features for training polarity classifiers for Twitter datasets have been researched in recent years with varying results. In this paper, we introduce a novel approach for automatically classifying and adding semantics as additional features the polarity of Twitter messages. These messages are classified as positive or negative or neutral with respect to a query term. The paper focuses on addressing polarity classification for product features in product reviews by building semantic association between product features and polarity words. The results show that our method is encouraging. Keywords— Corpus, tweet, analysis, sentiment, polarity, twitter
IT world is changing. Evolution of cloud computing in recent past has brought drastic change in e... more IT world is changing. Evolution of cloud computing in recent past has brought drastic change in era of IT field. Major advantage of cloud computing is that the hardware need not to be upgraded as Cloud Services provides everything of demand basis. Consuming electricity is the best example by which cloud computing can be explained, just pay for whatever you used. In this paper, we present a comparative study of leading cloud providers such as Amazon Cloud Services, Rackspace powered by OpenStack and other open source Cloud providers. Further discussing about how to implement OpenStack or just trying out by Devstack and Trystack just for testing purpose and at last covering releases and recent work going on in OpenStack. The aim of this paper is to show importance of OpenStack as a Cloud provider and how to get started with OpenStack.
This paper presents metal-fused filament fabrication (MF 3) for manufacturing Ti-6Al-4V parts by ... more This paper presents metal-fused filament fabrication (MF 3) for manufacturing Ti-6Al-4V parts by 3D printing of green parts followed by debinding and sintering to obtain mechanical properties comparable to metal injection-molded (MIM) specimens. The current work discusses critical material and process aspects of the MF 3 process that currently limits it from effective defect-free translation from 3D printed to sintering. We show successfully produced bound filament with 59 vol% of Ti-6Al-4V powder mixed with a polymeric binder system to print parts using MF 3. The feedstock and filaments showed uniform powder dispersion and acceptable flowability necessary for consistent extrusion during MF 3 printing, leading to defect-free parts. The green part density was 98.5 ± 0.6% relative to the density of the 59 vol% Ti-6Al-4V feedstock that resulted in successful debinding without slumping, no warpage, and layer delamination of the MF 3 parts. A two-step debinding combining solvent and thermal extraction of polymer binder followed by sintering in partial vacuum resulted in almost isotropic shrinkage of ~ 14% in all directions. The sintered density of these parts was 94.2 ± 0.1%. The mechanical properties of the present MF 3 processed Ti-6Al-4V alloy parts represent UTS of 875 ± 15 MPa and elongation of 17 ± 3%, which being 1.7% higher in UTS and 17.5% higher in elongation when compared to literature data for metal injection-molded parts.
Spectral amplitude coding optical code division multiple access (SAC-OCDMA) is one of the most im... more Spectral amplitude coding optical code division multiple access (SAC-OCDMA) is one of the most important multiplexing schemes of OCDMA that has turned out to be a stimulating investigating area in optical communication due to its increased privacy, network capacity and its flexibility in allocating the channels and asynchronous environment. On the other hand, Inter-satellite optical wireless communication (IsOWC) which is a favorable area of research in optical communication is useful for bursty transmissions and long-distance communications. In this paper, we have designed a hybrid SAC-OCDMA system through IsOWC channel using ZCC code for advanced intensity modulation formats (CSRZ, Db, and AMI). The investigation is done for four users at a bit rate of 40(4×10) Gb/s using a direct detection technique. Further, on comparing the proposed system using advanced intensity modulation formats, the result shows that system using CSRZ format is better in terms of BER, Q-factor, SNR and the...
Abstract This paper aims to break the current material-process-property tradeoffs in metal fused ... more Abstract This paper aims to break the current material-process-property tradeoffs in metal fused filament fabrication (MF3) to effectively fabricate Ti-6Al-4V alloy specimens beyond 90% relative density without any post-processing with consistent mechanical properties and microstructure, which are critical for aerospace and medical applications. Existing knowledge gaps in MF3 3D printing fail to address how properties scale from the filament processing stage to green part printing to sintering and what contributing factors cause significant deviation in mechanical properties in samples having the same sintered densities. To tackle these gaps, this work holistically investigates four key aspects specifically for MF3 of Ti-6Al-4V to address a) influence of filament extrusion conditions on filament density variance and diameter control, b) use of the design of experiments to identify factors influencing MF3 3D printed green sample density and dimensions, c) identifying sintering time and temperature conditions that yield densities beyond 90% and mechanical properties close to literature and d) how powder attributes (size and interstitial concentrations) and its effect on sintered density and mechanical properties for MF3 3D printed samples are discussed.
Journal of Materials Engineering and Performance, 2021
Building end-use functional metal parts by metal fused filament fabrication (MF 3) is an emerging... more Building end-use functional metal parts by metal fused filament fabrication (MF 3) is an emerging topic in additive manufacturing. MF 3 involves extrusion of polymer filaments that are highly filled with metal powder to print three-dimensional parts, followed by debinding and sintering to eliminate the polymer binder and get a fully dense metal part, respectively. Material properties, part design and processing conditions have a significant influence on the quality of MF 3 printed parts. Part distortion and dimensional variations are significant quality challenges that hinder the acceptance of printed parts in potential functional applications. Trial-and-error experiments to find the best conditions are commonly used for defect avoidance, though they are time-consuming and expensive. Hence, computational simulation and design solutions are required for MF 3 to enable a virtual analysis of the process outcome and reduce dependency on experimental methods. This paper investigates the applicability of a thermo-mechanical model for finite element simulation of the MF 3 printing process. The quantitative influence of material properties on MF 3 printed part quality was estimated using a simulation platform. The simulation results of two materials, a Ti-6Al-4V filled polymer and an unfilled ABS copolymer, were compared to experiments. It was determined that the unfilled polymer showed greater shrinkage and warpage than the Ti-6Al-4V filled polymer in simulations and experiments. Further, the trend in the distribution of warpage was consistent between experiments and simulation results for both materials. Finally, warpage compensation algorithms showed improvement in dimensional control for both materials in simulations and were consistent with experimental results.
Physica E: Low-dimensional Systems and Nanostructures, 2021
Abstract In this study, a backend gate GFET based sensor for the detection of COVID-19 via volati... more Abstract In this study, a backend gate GFET based sensor for the detection of COVID-19 via volatile organic compound biomarkers is designed and simulated. Graphene as the channel of the device is used as an adsorbing site for a biomarker, ethyl butyrate and the effect of the adsorption on the transport characteristics of the device is used as a sensing parameter. Functionalization of graphene with Platinum ameliorates the enticement between the biomarker and the host material calculated via adsorption energy. Density Functional Theory (DFT) is used to calculate the electronic and surface properties of the channel of the device, with and without adsorption of the biomarker. The calculated characteristic properties of the channel are used to figure out the transport properties of the device through COMSOL Multiphysics. Results show that adsorption of the biomarker on the functionalized graphene changes the dynamics of the charge carriers (via electronic properties) and results in variation in the transport properties of the device after adsorption of biomarker, making the device compatible for detection of COVID-19.
In this work, we have designed and simulated a graphene field effect transistor (GFET) with the p... more In this work, we have designed and simulated a graphene field effect transistor (GFET) with the purpose of developing a sensitive biosensor for methanethiol, a biomarker for bacterial infections. The surface of a graphene layer is functionalized by manipulation of its surface structure and is used as the channel of the GFET. Two methods, doping the crystal structure of graphene and decorating the surface by transition metals (TMs), are utilized to change the electrical properties of the graphene layers to make them suitable as a channel of the GFET. The techniques also change the surface chemistry of the graphene, enhancing its adsorption characteristics and making binding between graphene and biomarker possible. All the physical parameters are calculated for various variants of graphene in the absence and presence of the biomarker using counterpoise energy-corrected density functional theory (DFT). The device was modelled using COMSOL Multiphysics. Our studies show that the sensiti...
2021 IEEE 21st International Conference on Nanotechnology (NANO), 2021
In this study, we probe the surface engineered (vacancy and Stone Wales defective) hydrogen passi... more In this study, we probe the surface engineered (vacancy and Stone Wales defective) hydrogen passivated armchair graphene nanoribbon with a width of 7 atoms as a biosensing material to detect methanethiol biomarkers. Induction of defects results in the decrement of the bandgap by the formation of the trapping states. After geometry optimisation, it is found that only vacancy induced armchair graphene nanoribbon can form strong binding with the biomarker, whereas Stone Wales defect induced armchair graphene nanoribbon show disassociation with the biomarker by having positive adsorption energy. Using density functional theory, the electronic properties of a vacancy-induced armchair graphene nanoribbon with and without adsorption of methanethiol are calculated, showing that methanethiol adsorption leads to increment in the bandgap of the host material by eliminating the trapping states. The work function and electron affinity change after adsorption. As there are significant changes in the electronic properties, vacancy induced armchair graphene nanoribbon show high sensing capabilities toward methanethiol biomarkers.
Density functional theory-based first-principles investigation is performed on pristine and mono ... more Density functional theory-based first-principles investigation is performed on pristine and mono vacancy induced GaAs nanoribbons to detect the presence of three volatile organic compounds (VOCs), aniline, isoprene and o-toluidine, which will aid in sensing lung cancer. The study has shown that pristine nanoribbon senses all three analytes. For the pristine structure, we observe decent adsorbing parameters and the bandgap widens after the adsorption of analytes. However, the introduction of the carrier traps induced by defect causes deep energy wells that vary the electrical properties as indicated in the bandgap analysis of GaAs, wherein adsorption of aniline and o-toluidine reduces the bandgap to 0 eV, making the structure highly conductive in nature. The adsorption energies of defect-induced nanoribbon are more as compared with the pristine counterpart. Nonetheless, the introduction of defects has improved the sensitivity further.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
In order to achieve large capacity inter-satellite communication, optical wireless communication ... more In order to achieve large capacity inter-satellite communication, optical wireless communication (OWC) is emerging as a promising area of research amongst the academic and research groups. While radio over fiber (ROF) and advanced modulation technique is considered to be a key enabling technology in the development of OWC based access networks for high-speed data transmission. This paper has proposed a novel ROF based system model using OWC for long haul high data rate applications. This system is designed using differential quadrature phase shift keying (DQPSK) through inter-satellite optical wireless communication (IsOWC) channel. The verification of the performance is performed at bit rates of 100 and 200 Gbps over a space distance range up to 1000 to 50000 km under different transmitted power. The simulative investigation has been carried out in terms of important parameters like BER, Q-factor and eye diagrams.
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