Browsing by Author "Kumar P."

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3D text segmentation and recognition using leap motion
(2017) Kumar P.; Saini R.; Roy P.P.; Dogra D.P.
In this paper, we present a method of Human-Computer-Interaction (HCI) through 3D air-writing. Our proposed method includes a natural way of interaction without pen and paper. The online texts are drawn on air by 3D gestures using fingertip within the field of view of a Leap motion sensor. The texts consist of single stroke only. Hence gaps between adjacent words are usually absent. This makes the system different as compared to the conventional 2D writing using pen and paper. We have collected a dataset that comprises with 320 Latin sentences. We have used a heuristic to segment 3D words from sentences. Subsequently, we present a methodology to segment continuous 3D strokes into lines of texts by finding large gaps between the end and start of the lines. This is followed by segmentation of the text lines into words. In the next phase, a Hidden Markov Model (HMM) based classifier is used to recognize 3D sequences of segmented words. We have used dynamic as well as simple features for classification. We have recorded an overall accuracy of 80.3 % in word segmentation. Recognition accuracies of 92.73 % and 90.24 % have been recorded when tested with dynamic and simple features, respectively. The results show that the Leap motion device can be a low-cost but useful solution for inputting text naturally as compared to conventional systems. In future, this may be extended such that the system can successfully work on cluttered gestures. � 2016, Springer Science+Business Media New York.
Analysis of EEG signals and its application to neuromarketing
(2017) Yadava M.; Kumar P.; Saini R.; Roy P.P.; Prosad Dogra D.
Marketing and promotions of various consumer products through advertisement campaign is a well known practice to increase the sales and awareness amongst the consumers. This essentially leads to increase in profit to a manufacturing unit. Re-production of products usually depends on the various facts including consumption in the market, reviewer�s comments, ratings, etc. However, knowing consumer preference for decision making and behavior prediction for effective utilization of a product using unconscious processes is called �Neuromarketing�. This field is emerging fast due to its inherent potential. Therefore, research work in this direction is highly demanded, yet not reached a satisfactory level. In this paper, we propose a predictive modeling framework to understand consumer choice towards E-commerce products in terms of �likes� and �dislikes� by analyzing EEG signals. The EEG signals of volunteers with varying age and gender were recorded while they browsed through various consumer products. The experiments were performed on the dataset comprised of various consumer products. The accuracy of choice prediction was recorded using a user-independent testing approach with the help of Hidden Markov Model (HMM) classifier. We have observed that the prediction results are promising and the framework can be used for better business model. � 2017, Springer Science+Business Media New York.
Analysis of M-PSK with MRC receiver over ? - ? fading channels with outdated CSI
(2014) Kumar P.; Sahu P.R.
Average-symbol-error rate (ASER) and diversity gain of an L-branch maximal ratio combining (MRC) receiver for M-ary phase-shift keying (M-PSK) modulation are analyzed over ?-? fading channels with outdated channel state information using moment generating function (MGF) based approach. Analytical expressions for the MGFs of the exact and asymptotic signal-to-noise ratio at the output of the MRC receiver are obtained using which analytical expressions for the ASER and diversity gain are derived. The effects of ?, ?, and L on the ASER and diversity gain are analyzed. � 2014 IEEE.
Autogenous tungsten inert gas and gas tungsten Arc with filler welding of dissimilar P91 and P92 steels
(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
Creep strength ferritic/martensitic modified 9Cr-1Mo-V-Nb (P91) steel also designated as ASTM A335 and P92 steel are used for piping, cladding, ducts, wrappers, and the pressure vessel in Gen IV nuclear reactors. In the present investigation, a comparative study of the effect of autogenous tungsten inert gas welding (A-TIG) with double pass and multipass gas tungsten arc (GTA) welding with filler on microstructure evolution in the weld fusion zone and the mechanical properties of P91 and P92 steel welded joints was carried out. The microstructure evolution was studied in as-welded and postweld heat treatment (PWHT) condition. The study also focused on the evolution of d-ferrite patches and their influence on the tensile properties of welded joints. PWHT was carried out at 760 C with durations from 2 to 6 h. To study the effect of d-ferrite evolution on mechanical properties, Charpy toughness, microhardness, and tensile tests were performed. The acceptable microstructure and mechanical properties were obtained after the 6 h of PWHT for A-TIG arc welding process while for GTA weld with filler wire, it was obtained after the 2 h of PWHT at 760 C. � 2018 by ASME.
A bio-signal based framework to secure mobile devices
(2017) Kumar P.; Saini R.; Pratim Roy P.; Prosad Dogra D.
Nowadays, mobile devices are often equipped with high-end processing units and large storage space. Mobile users usually store personal, official, and large amount of multimedia data. Security of such devices are mainly dependent on PIN (personal identification number), password, bio-metric data, or gestures/patterns. However, these mechanisms have a lot of security vulnerabilities and prone to various types of attacks such as shoulder surfing. The uniqueness of Electroencephalography (EEG) signal can be exploited to remove some of the drawbacks of the existing systems. Such signals can be recorded and transmitted through wireless medium for processing. In this paper, we propose a new framework to secure mobile devices using EEG signals along with existing pattern-based authentication. The pattern based authentication passwords are considered as identification tokens. We have investigated the use of EEG signals recorded during pattern drawing over the screen of the mobile device in the authentication phase. To accomplish this, we have collected EEG signals of 50 users while drawing different patterns. The robustness of the system has been evaluated against 2400 unauthorized attempts made by 30 unauthorized users who have tried to gain access of the device using known patterns of 20 genuine users. EEG signals are modeled using Hidden Markov Model (HMM), and using a binary classifier implemented with Support Vector Machine (SVM) to verify the authenticity of a test pattern. Verification performances are measured using three popular security matrices, namely Detection Error Trade-off (DET), Half Total Error Rate (HTER), and Receiver Operating Characteristic (ROC) curves. Our experiments revel that, the method is promising and can be a possible alternative to develop robust authentication protocols for hand-held devices. � 2017 Elsevier Ltd
A brief study on ?-ferrite evolution in dissimilar P91 and P92 steel weld joint and their effect on mechanical properties
(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.; Thakre J.G.; Vidyarthy R.S.; Narang H.K.
Ferritic/martensitic 9Cr-1Mo-V-Nb steel also designated as ASTM A335 used in construction of several components of power plants operating in temperature range of 600�650 �C. In present investigation, dissimilar weld joint of P91 and P92 steel were prepared using the autogenous tungsten inert gas (A-TIG) welding and multi-pass gas tungsten arc welding (GTAW) process. A comparative study was performed on evolution of ?-ferrite patches in weld fusion zone and heat affected zones (HAZs) of welded joints. The evolution of ?-ferrite patches was studied in as-welded and post-weld heat treatment (PWHT) condition. PWHT was carried out at 760 �C for tempering time of 2 h and 6 h, for both A-TIG and GTA weld joints. It was observed that presence of higher content of ferrite stabilizer in P92 steel promote the formation of ?-ferrite patches in weld fusion zone as well as HAZs. To study the effect of welding process and PWHT, Charpy V impact energy and microhardness tests were performed. For microstructure characterization, field-emission scanning electron microscope (FESEM) and optical microscope were utilized. � 2017 Politechnika Wroc?awska
Characterisation of dissimilar P91 and P92 steel welds joint
(2019) Pandey C.; Mahapatra M.M.; Kumar P.
In the present study, dissimilar weld joint was prepared using the P91 and P92 steel plate of 8-mm thickness, using the multi-pass gas tungsten arc (GTA) welding with filler (weld 1) and autogenous tungsten inert gas welding (A-TIG) process (weld 2). Evolution of ?-ferrite patches was studied in weld zone and heat affected zone (HAZ) for both weld 1 and weld 2. Effect of varying post weld heat treatment (PWHT) duration was also studied on ?-ferrite patches and mechanical properties of the dissimilar weld joint. PWHT was carried out at 760�C. For weld 2, weld zone showed poor impact toughness and higher peak hardness as compared to weld 1. After the PWHT, a considerable reduction in hardness was obtained for both weld 1 and weld 2,while impact toughness of weld zone showed a continuous increment with PWHT duration. For weldments characterisation, optical microscope, scanning electron microscope (SEM) and microhardness tester were utilised. � 2018, � 2018 Informa UK Limited, trading as Taylor & Francis Group.
Characterization of Cast and Forged (C&F) Gr. 91 Steel in Different Heat Treatment Condition
(2017) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
The present research work deals with the results of influence of different heat treatment conditions on the microstructure stability and mechanical properties of high-chromium X10CrMoVNNB9-1(P91) cast and forged (C&F) P91 steel. The C&F P91 steel was subjected to various tempering condition in the temperature range of 350�760 �C and tempering time of 2 h, after the normalizing at 1040 �C for 40 min. The steel was also subjected to furnace cooled and water quenched heat treatment. Tempering at 650 and 760 �C produced the fully tempered lath martensitic structure with M23C6, M7C3, M3C and MX precipitates along the prior austenite grain boundaries, lath boundaries and matrix region. Tempering at 350 and 1000 �C produced the partially tempered columnar laths and untempered columnar laths martensite, respectively. The tempering time was also varied from 2 to 8 h for fixed tempering temperature of 760 �C. The optimum microstructure evolution was obtained for 6 h of tempering at 760 �C that led to improved mechanical properties. � 2017 The Indian Institute of Metals - IIM
Characterization of microstructure of HAZs in as-welded and service condition of P91 pipe weldments
(2017) Pandey C.; Giri A.; Mahapatra M.M.; Kumar P.
Steels 9-12% Cr, having the high creep rupture strength are advocated for the modern low polluting thermal power plants. In the present investigation, the P91 pipe weldments have been characterized for microstructural responses in as-welded, post-weld heat treatment (PWHT) and ageing conditions. The PWHT of welded samples were carried out at 760 �C for time of 2 h and ageing at 760 �C for 720 h and 1440 h, respectively. The effect of time has been studied on precipitates size, distribution of precipitates and grain sizes present in various zones of P91 steel weldments. The impact toughness and hardness variation of heat affected zone (HAZ) have also been studied in as-welded condition as well as at different heat treatment condition. A significant change was observed in grain size and precipitates size after each heat treatment condition. The maximum impact toughness of HAZ was obtained after PWHT at 760 �C for 2 h. The main phase observed in weld fusion zone in as-welded, PWHT and ageing conditions were M23C6, MX, M7C3, Fe-rich M3C and M2C. The unwanted Z-phase (NbCrN) was also noticed in weld fusion zone after ageing of 1440 h. � 2017, The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.
Characterization of weld fusion zone for TIG welded p91 and P92 steels
(2018) Pandey C.; Mohan Mahapatra M.; Kumar P.; Kumar P.; Thakare J.G.
The welding of nuclear grade P91 and P92 steel plate of thickness 5.2 mm were performed using the autogenous tungsten inert gas (TIG) welding process. The welded joint of P91 and P92 steel plate were subjected to the varying post weld heat-treatment (PWHT) including the post weld heat treatment (PWHT) and re-austenitizing based tempering (PWNT). A comparative study was performed related to the microstructure evolution in fusion zone (FZ) of both the welded joint using the scanning electron microscope and optical microscope in a different condition of heat treatment. The hardness test of the FZ for both joints was also conducted in a different condition of heat treatment. P92 steel welded joint have observed the higher tendency of the ? ferrite formation that led to the great variation in hardness of the P92 FZ. The homogeneous microstructure (absence of ? ferrite) and acceptable hardness was observed after the PWNT treatment for both the welded joint. � 2018 Polish Academy of Sciences. All Rights Reserved.
Comparative study of autogenous tungsten inert gas welding and tungsten arc welding with filler wire for dissimilar P91 and P92 steel weld joint
(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
Creep strength enhanced ferritic/martensitic 9Cr-1Mo-V-Nb (P91) steel is also designated as ASTM A335 used for out-of-core and in-core (piping, cladding, ducts, wrappers, and pressure vessel) of Gen IV reactors. In present investigation, the dissimilar weld joint of P91 and P92 steel were made using the autogenous tungsten inert gas (TIG) welding with single pass, double side pass and multi-pass gas tungsten arc (GTA) welding with filler wire. Microstructure evolution in sub-zones and mechanical properties of dissimilar welded joints were studied in as-welded and post weld heat treatment (PWHT) condition. Formation of ?-ferrite patches in weld fusion zone and heat affected zones (HAZs) and their influence on the mechanical behaviour of the welded joints were also studied. Presence of higher content of ferrite stabilizer in P92 steel have resulted the formation of ?-ferrite patches in weld fusion zone as well as HAZs. The ?-ferrite was observed in autogenous TIG welds joints. The ?-ferrite patches were formed in as-welded condition and remained in the microstructure after the PWHT. The ?-ferrite patches leads to reduction in Charpy toughness of autogenous TIG welds joint and also lower down the average hardness of weld fusion zone. Peak hardness and poor impact toughness were observed for autogenous TIG welds joint as compared to GTA welds. For microstructure characterization, field-emission scanning electron microscope (FESEM) with energy dispersive spectroscopy (EDS) and optical microscope were utilized. � 2017 Elsevier B.V.
A comparative study of ductile-brittle transition behavior and fractography of P91 and P92 steel
(2017) Saini N.; Pandey C.; Mahapatra M.M.; Narang H.K.; Mulik R.S.; Kumar P.
The modified 9Cr-1Mo (P91) and 9Cr- 0.5Mo- 1.8W (P92) steel used in fast breeder reactor is exposed to irradiation during service which severely affects the dynamic fracture resistance by increasing the ductile to brittle transition temperature (DBTT). Thus, even at room temperature, the steel can become brittle and prone to cracking. In the present investigation, to elucidate the influence of low temperature on the DBTT, Charpy toughness test was performed on creep strength enhanced ferritic P91 and P92 steel. Lower DBTT was observed for the P92 steel as compared to P91 steel. To find the mode of fracture, the fractured Charpy toughness specimens were investigated using a field electron scanning electron microscope (FESEM). The fracture surface revealed the brittle mode of fracture at a lower temperature for both the steels while the mixed mode of fracture was noticed at room temperature and above. � 2017 Elsevier Ltd
A comparative study of transverse shrinkage stresses and residual stresses in P91 welded pipe including plasticity error
(2018) Pandey C.; Mahapatra M.M.; Kumar P.
The paper deals with the measurement of the residual stresses in P91 welded pipe using the blind hole drilling technique. The P91 pipe weld joints were prepared using gas tungsten arc welding process. The residual stress measurement was carried out using the strain gauge rosette that was associated with the plastic deformation of material and stress concentration effect of multi-point cutting tool. Strain gauge response was estimated experimentally using the tensile testing for the uniaxial loading while finite element analysis was performed for biaxial loading. Gas tungsten arc welds joint was prepared for conventional V-groove and narrow groove design. The corrective formulation was developed for calculating the corrected value of residual stresses from the experimentally obtained strain value. The corrected and experimental induced residual stresses values as per ASTM E837-13 were calculated for both V-groove and narrow groove design. Post weld heat treatment (PWHT) of P91 welded pipe was also conducted to study their effect on residual stresses. � 2018 Politechnika Wroc?awska
Corrigendum to �A brief study on ?-ferrite evolution in dissimilar P91 and P92 steel weld joint and their effect on mechanical properties� [Archives of Civil and Mech Engineering 18 (2018)713�722](S1644966517301814)(10.1016/j.acme.2017.12.002)
(2019) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.; Thakare J.G.; Vidyathy R.S.; Narang H.K.
The authors regret that The authors regret for any inconvenience caused. � 2019 Politechnika Wroc?awska
Coupled HMM-based multi-sensor data fusion for sign language recognition
(2017) Kumar P.; Gauba H.; Roy P.P.; Dogra D.P.
Recent development of low cost depth sensors such as Leap motion controller and Microsoft kinect sensor has opened up new opportunities for Human-Computer-Interaction (HCI). In this paper, we propose a novel multi-sensor fusion framework for Sign Language Recognition (SLR) using Coupled Hidden Markov Model (CHMM). CHMM provides interaction in state-space instead of observation states as used in classical HMM that fails to model correlation between inter-modal dependencies. The framework has been used to recognize dynamic isolated sign gestures performed by hearing impaired persons. The dataset has been tested using existing data fusion approaches. The best recognition accuracy has been achieved as high as 90.80% with CHMM. Our CHMM-based approach shows improvement in recognition performance over popular existing data fusion techniques. � 2016 Elsevier B.V.
Dissimilar joining of CFEF steels using autogenous tungsten-inert gas welding and gas tungsten arc welding and their effect on ?-ferrite evolution and mechanical properties
(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
Ferritic/martensitic 9Cr-1Mo-V-Nb steel also designated as ASTM A335 used in construction of several components of power plants operating in temperature range of 600�650 �C. In present investigation, dissimilar weld joints of P91 and P92 steel were prepared using the autogenous tungsten inert gas welding (A-TIG) and multi-pass gas tungsten arc (GTA) welding process. A comparative was performed on evolution of ?-ferrite patches in weld fusion zone and heat affected zone (HAZ) of welded joints. The evolution of ?-ferrite patches was carried out in as-welded and post-weld heat treatment (PWHT) condition. PWHT was carried out at 760 �C for 2 h for both A-TIG and GTA welding process. For A-TIG weld joint higher yield strength, ultimate tensile strength (UTS) and peak hardness were measured due to higher heat input in single pass and higher carbon content in weld fusion zone. Higher heat input, fast cooling rate and higher weight percentage of ferrite stabilizer like vanadium (V) and niobium (Nb) in A-TIG weld joint were resulted in formation ferrite patches in weld fusion zone and heat affected zone. Higher weight percentage of V and Nb in A-TIG weld zone was resulted poor impact toughness of A-TIG weld fusion zone than GTA welds in as-welded condition. After the PWHT at 760 �C�2 h, Charpy toughness of A-TIG weld fusion zone (48 J) just meet the minimum required value as required by the EN: 1557:1997 (47 J). � 2017
Effect of cobalt substitution on structural, impedance, ferroelectric and magnetic properties of multiferroic Bi2Fe4O9 ceramics
(2016) Mohapatra S.R.; Sahu B.; Chandrasekhar M.; Kumar P.; Kaushik S.D.; Rath S.; Singh A.K.
Structural, impedance, ferroelectric and magnetic properties were examined in multiferroic Bi2Fe4(1?x)Co4xO9 (0?x?0.02) ceramics synthesized via solid-state reaction method. X-ray diffraction analysis and Rietveld refinement showed secondary phase formation (for x?0.01) which was subsequently confirmed from room temperature Raman spectroscopy study. The frequency dependence of impedance and electric modulus of the material showed the presence of non-Debye type relaxation in all the samples. The values of the activation energies calculated from imaginary impedance and modulus lay in the range of 0.92�0.99�eV which confirmed that the oxygen vacancies play an important role in the conduction mechanism. Moreover, suitable amount of Co substitution significantly enhanced the remnant polarization (2Pr) from 0.1193�?C/cm2 (x=0) to 0.2776�?C/cm2 (x=0.02). Besides, room temperature M-H measurement showed improved ferromagnetic hysteresis loop for all the modified samples. The remnant magnetization (Mr) and coercive field (Hc) increased from 0.0007�emu/gm and 42�Oe for x=0�0.1401�emu/gm and 296�Oe for x=0.02. The improved ferroelectricity was due to Co 3d-O 2p hybridization and enhanced magnetization originated from the partial substitution of Co3+ ions leading to breakdown of balance between the anti-parallel sub lattice magnetization of Fe3+ ions. � 2016 Elsevier Ltd and Techna Group S.r.l.
Effect of cooling medium on microstructure evolution and tensile properties of creep-strength-enhanced ferritic steel
(2018) Pandey C.; Saini N.; Thakre J.G.; Mahapatra M.M.; Kumar P.
In creep-strength-enhanced ferritic steels, hydrogen-induced cold cracking of weldments is a serious issue. In the present research work, the effect of cooling medium on tensile properties and microstructure evolution of P91 steel weldments has been studied. For water-cooling condition, the diffusible hydrogen metal in deposited metal was measured by the mercury method. The microstructure of weldments in different cooling condition was characterized by using the field-emission scanning electron microscope (FE-SEM) and optical microscope. The fractured tensile test samples were characterized using the FE-SEM. The maximum tensile strength was measured to be 624 MPa for air-cooling medium (very low level of diffusible hydrogen). � 2018 Sociedade Portuguesa de Materiais (SPM)
Effect of creep phenomena on room-temperature tensile properties of cast & forged P91 steel
(2017) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
In present research work, the as-received cast & forged (C&F) P91 steel was subjected to the creep test at temperature of 620 �C and 650 �C for applied stress of 120 MPa. The room temperature tensile test was conducted after normalizing and tempering (N&T) treatment of the ruptured creep specimen. The standard tensile-test specimen was prepared from the gauge section of creep ruptured specimen. The N&T treatment was performed to restore the microstructure and mechanical properties of virgin P91 steel (N&T P91 steel). The microstructure of creep fractured specimen in ruptured state and N&T condition were characterized by using field-emission scanning electron microscope (FE-SEM) with energy dispersive X-ray spectroscopy (EDS). The fracture surface morphology of crept specimen and the tensile tested specimen was also studied. The effect of prior creep deformation on the mechanical strength was more significant in the sample with longer creep rupture life. � 2017
Effect of normalization and tempering on microstructure and mechanical properties of V-groove and narrow-groove P91 pipe weldments
(2017) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
In Very High Temperature Reactor (VHTR), The Nb-V modified 9Cr-1Mo (P91) creep strength enhanced ferritic (CSEF) steel is currently considered as a candidate material for reactor internals and reactor pressure vessels (RPVs). After the welding of P91 steel, the inhomogeneous microstructure of weldment is a serious issue because it promotes the well-known Type IV cracking in P91 weldments. The present research work is focused on how the microstructure evolve in various zone of P91 pipe weldment during the sub-critical post weld heat treatment (PWHT) and normalized and tempered (N&T) heat treatment. The effect of PWHT and N&T heat treatment are also considered on tensile properties and hardness variation of P91 weldments. To characterize the sample scanning electron microscope (SEM), X-ray diffraction (XRD) and optical micrograph was used. It was observed that the N&T heat treatment provides the homogeneous microstructure compared to PWHT. The superior mechanical properties was also measured in N&T condition compared to PWHT. Study of fracture surface morphology of tensile tested specimen in different heat treatment condition is also presented. � 2017 Elsevier B.V.