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- 검색키워드
- 저자 : Sandeep Gupta (검색결과 42 건)
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Sandeep Kumar Gupta,R. Manna,Kausik Chattopadhyay 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.9
In the present study, carbide-free nanostructured bainite is produced by austempering high carbon and silicon steels at 250 °C. Fine pearlitic structure is also made by patenting the steels of selected compositions at 550 °C. The formation of carbidefreenanostructured bainite and retained austenite in the austempered steels and ferrite and cementite in patented steels wereconfirmed through X-ray diffraction and TEM studies. The optical, scanning and transmission electron microscopies revealthe presence of nanoscale bainite, filmy and blocky austenite in austempered steels and the presence of lamellar pearlite inpatented steels. Increasing austempering time enhances the amount of bainite but decreases the blocky retained austenite. Thecorrosion behaviour of the newly developed bainitic steels is compared with that of pearlitic steel of the same compositions. Electrochemical and immersion corrosion tests are conducted in an aqueous 3.5% NaCl solution. The corroded surfaces areanalyzed with the scanning electron microscope (SEM) and X-ray photoelectron spectrometer (XPS). Corrosion resistanceincreases with increasing carbon percentage due to the formation of magnetite (Fe3O4), provided the content of other alloyingelements remains the same. The presence of Ni decreases corrosion rate significantly, i.e., enhances corrosion resistance,charge transfer resistance (Rct) and polarization resistance (Rp). Reducing retained austenite in nanostructured steel decreasesthe corrosion rate due to the lesser area of Galvanic couples and the formation of uniform, compact, and non-porous passivelayer. The bainitic steel samples demonstrated superior corrosion resistance to that of the pearlitic steel due to lesser cellformation. The corrosion mechanisms of high-carbon bainitic and pearlitic steel are discussed.
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Design and Research of Digital Image Forensics Algorithm
Sandeep Gupta 한국컴퓨터게임학회 2021 한국컴퓨터게임학회논문지 Vol.34 No.3
With the wide application of camera equipment, digital image, as an important information carrier, has gradually integrated into me their lives. With the popularity of image editing software, people have to re-examine seeing is believing ideas. In recent years, there have been frequent incidents of image fraud in the fields of news media, judicial notarization and scientific research. Therefore, judging the authenticity and originality of digital images has become an urgent problem to be solved in the field of forensics. Tamper often change the image and its information through different image operations which affecting the reader s authenticity of things. Therefore, it is of great significance to detect the operation history of digital images. Based on the above research background, this paper first summarizes the research status of image operation forensics algorithm, and then obtains evidence from digital image muti-operation. The accuracy, practicability and robustness of the algorithm are proposed. In this paper, an image muti-operation forensics method with JPEG robustness is proposed. Experiments show that this method has a good performance in JPEG robust detection with high quality factor and low quality factor.
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Optimization of InAlAs/InGaAs HEMT Performance for Microwave Frequency Applications and Reliability
Gupta, Ritesh,Aggarwal, Sandeep Kumar,Gupta, Mridula,Gupta, R.S. The Institute of Electronics and Information Engin 2004 Journal of semiconductor technology and science Vol.4 No.3
In the present paper efforts have been made to optimize InAlAs/InGaAs HEMT by enhancing the effective gate voltage ($(V_c-V_off)$) using pulsed doped structure from uniformly doped to delta doped for microwave frequency applications and reliability. The detailed design criteria to select the proper design parameters have also been discussed in detail to exclude parallel conduction without affecting the del ice performance. Then the optimized value of $V_c-V_off$and breakdown voltages corresponding to maximum value of transconductance has been obtained. These values are then used to predict the transconductance and cut-off frequency of the del ice for different channel depths and gate lengths.
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Gupta, Ritesh,Aggarwal, Sandeep Kr,Gupta, Mridula,Gupta, R.S. The Institute of Electronics and Information Engin 2006 Journal of semiconductor technology and science Vol.6 No.3
A new analytical model has been proposed for predicting the sheet carrier density of Metal insulator Semiconductor High Electron Mobility Transistor (MISHEMT). The model takes into account the non-linear relationship between sheet carrier density and quasi Fermi energy level to consider the quantum effects and to validate it from subthreshold region to high conduction region. Then model has been formulated in such a way that it is applicable to MESFET/HEMT/MISFET with few adjustable parameters. The model can also be used to evaluate the characteristics for different gate insulator geometries like T-gate etc. The model has been extended to forecast the drain current, conductance and high frequency performance. The results so obtained from the analysis show excellent agreement with previous models and simulated results that proves the validity of our model.
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Gupta, Ritesh,Aggarwal, Sandeep Kumar,Gupta, Mridula,Gupta, R.S. The Institute of Electronics and Information Engin 2007 Journal of semiconductor technology and science Vol.7 No.2
A comprehensive short channel analytical model has been proposed for High Electron Mobility Transistor (HEMT) to obtain higher cut-off frequency maintaining the reliability of the device. The model has been proposed to consider generalized doping variation in the directions perpendicular to and along the channel. The effect of field plates and different gate-insulator geometry (T-gate, etc) have been considered by dividing the area between gate and the high band gap semiconductor into different regions along the channel having different insulator and metal combinations of different thicknesses and work function with the possibility that metal is in direct contact with the high band gap semiconductor. The variation obtained by gate-insulator geometry and field plates in the field and channel potential can be produced by varying doping concentration, metal work-function and gate-stack structures along the channel. The results so obtained for normal device structure have been compared with previous proposed model and numerical method (finite difference method) to prove the validity of the model.
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Gupta, Ritesh,Kaur, Ravneet,Aggarwal, Sandeep Kr,Gupta, Mridula,Gupta, R.S. The Institute of Electronics and Information Engin 2010 Journal of semiconductor technology and science Vol.10 No.1
Improvement in breakdown voltage ($BV_{ds}$) and speed of the device are the key issues among the researchers for enhancing the performance of HEMT. Increased speed of the device aspires for shortened gate length ($L_g$), but due to lithographic limitation, shortening $L_g$ below sub-micrometer requires the inclusion of various metal-insulator geometries like T-gate onto the conventional architecture. It has been observed that the speed of the device can be enhanced by minimizing the effect of upper gate electrode on device characteristics, whereas increase in the $BV_{ds}$ of the device can be achieved by considering the finite effect of the upper gate electrode. Further, improvement in $BV_{ds}$ can be obtained by applying field plates, especially at the drain side. The important parameters affecting $BV_{ds}$ and cut-off frequency ($f_T$) of the device are the length, thickness, position and shape of metal-insulator geometry. In this context, intensive simulation work with analytical analysis has been carried out to study the effect of variation in length, thickness and position of the insulator under the gate for various metal-insulator gate geometries like T-gate, $\Gamma$-gate, Step-gate etc., to anticipate superior device performance in conventional HEMT structure.
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Sandeep Gupta,Attaullah Buriro,Bruno Crispo 한국통신학회 2019 ICT Express Vol.5 No.1
On-demand ride services and the rideshare infrastructure primarily focus on the minimization of travel time and cost. However, the safety of riders is overlooked by service providers. For driver authentication, existing identity management methods typically check the driving license, which can be easily stolen, forged, or misused. Further, background checks are not performed at all; instead, social profiles and peer reviews are used to foster trust, thereby compromising the safety and security of riders. Moreover, the present mechanism seems ineffective in discontinuing a malicious driver from offering the services. In this paper, we present DriverAuth—a fully transparent and easy-to-use authentication scheme for drivers that is based on common behavioral biometric modalities, such as hand movements, swipes, and touch-strokes while the drivers interact with the dedicated smartphone-based application for accepting the booking. A preliminary study of behavioral biometric-based approaches offers a usable verification mechanism on smartphones that could be a potential solution to improve the safety of riders in the emerging on-demand ride and the rideshare infrastructure.
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On Deferred f-statistical Convergence
Gupta, Sandeep,Bhardwaj, Vinod K. Department of Mathematics 2018 Kyungpook mathematical journal Vol.58 No.1
In this paper, we generalize the concept of deferred density to that of deferred f-density, where f is an unbounded modulus and introduce a new non-matrix convergence method, namely deferred f-statistical convergence or $S^f_{p,q}$-convergence. Apart from studying the $K{\ddot{o}}the$-Toeplitz duals of $S^f_{p,q}$, the space of deferred f-statistically convergent sequences, a decomposition theorem is also established. We also introduce a notion of strongly deferred $Ces{\grave{a}}ro$ summable sequences defined by modulus f and investigate the relationship between deferred f-statistical convergence and strongly deferred $Ces{\grave{a}}ro$ summable sequences defined by f.
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Sandeep Kumar,Sandeep Garg,Seema Gupta 대한치과보철학회 2013 The Journal of Advanced Prosthodontics Vol.5 No.1
PURPOSE. The purpose of this study was to determine accurately the part of the tragus to be used to form the Ala-Tragal line or Camper’ line in orthognathic profile patients. MATERIALS AND METHODS. 150 dentate subjects with age of 18-40 years with orthognathic profile were sampled. Life-size lateral digital photographs of the face with fox plane were taken in natural head position. Different angles between Eye-Ear plane and occlusal plane (OT1-OP), Eye-Ear plane and ala-superior border of tragus (OT1-AT1), Eye-Ear plane and ala-middle border of tragus (OT1-AT2) and Eye-Ear plane and ala-inferior border of tragus (OT1-AT3) were calculated using computer software package, AutoCAD 2004. From the three angles formed by the Eye-ear plane (OT1 or FH plane) and the ala-tragal lines, the one closest to the angle formed between Eye-Ear plane (OT1) and occlusal plane (OP) was used to determine the occlusal plane of orientation. The obtained results were subjected to ANOVA F test, Tukey’ Honestly significant difference test, followed by Karl Pearson coefficient of correlation test. P values of less than 0.05 were taken as statistically significant. RESULTS. The mean of base line angle i.e. OT1-OP angle (11.96 ± 4.36) was found to be close to OT1-AT2 angle (13.67 ± 1.93) and OT1-AT3 angle (10.31 ± 2.03), but OT1-OP angle was found to be more closer to OT1-AT3 angle. Comparison of mean angles showed that OT1-OP angle in both males (11.68) and females (12.51) is close to OT1-AT3 angle (males- 11.01, females- 11.95). CONCLUSION. The line joining from ala to the lower border of the tragus was parallel to the occlusal plane in 53.3% of the subjects. There was no influence of the sex on the level of occlusal plane.
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