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Singh, V.,Sivaramaiah, G.,Mohapatra, M.,Rao, J. L.,Singh, N.,Pathak, M. S.,Singh, P. K.,Dhoble, S. J. Springer Science + Business Media 2017 Journal of Electronic Materials Vol.46 No.2
<P>GdAlO3 phosphor samples have been prepared by a solution combustion method. X-ray diffraction analysis revealed that the GdAlO3 phosphor stabilized in orthorhombic phase. The optical absorption spectrum showed bands due to Gd3+ ions as well as defect level in the host. The excitation spectrum exhibited a dominant band with maximum at 273 nm. Upon excitation at 273 nm, ultraviolet-B (UV-B) emission with maximum at 312 nm was observed from the undoped sample, being attributed to P-6(7/2) -> S-8(7/2) transition of Gd3+ ion. The UV-B emission was enhanced at liquid-nitrogen temperature (77 K), most probably due to increased ground-state population according to the Boltzmann distribution law. Electron spin resonance spectra of samples at both room and liquid-nitrogen temperature exhibited resonance signals at g ae 2, attributed to Gd3+ ions arranged with octahedral symmetry linked via oxygen bridges. Various magnetic and thermodynamic parameters for the phosphor system were evaluated by standard procedures. Correlation of these values with the optical properties suggested that the GdAlO3 phosphor can be effectively used as an UV-B light source for industrial applications at room temperature.</P>
Fault accommodation in compliant quadruped robot through a moving appendage mechanism
Gor, M.M.,Pathak, P.M.,Samantaray, A.K.,Yang, J.-M.,Kwak, S.W. Elsevier 2018 Mechanism and machine theory Vol.121 No.-
<P><B>Abstract</B></P> <P>Quadruped robots provide better stability and speed in comparison to other legged robots. However, its joint actuator or sensor failure severely affects locomotion. Strategies for actuator and sensor fault accommodation in a compliant legged quadruped are presented here. A pair of orthogonally mounted moving appendages mechanism is proposed here to accommodate locked joint failure. These appendages as rack mounted inertias perform controlled motion during actuator failure. A strategy for sensor fault accommodation is also presented. A three-dimensional multi-body dynamics model of quadruped robot and its fault accommodation strategies are developed using bond graph modeling approach. The control performance is validated both through simulations and experiments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Locked-joint and sensor faults of a quadruped robot are detected and isolated. </LI> <LI> Fault tolerant operation of a quadruped robot is considered for various missions. </LI> <LI> Actuator faults are accommodated with controlled moving appendages. </LI> <LI> Sensor fusion is used to reconstruct faulty sensor data. </LI> <LI> Online system reconfiguration is validated using simulations and experiments. </LI> </UL> </P>
Posture Control Strategy of a Platform using a RP Manipulator
M. M. Gor,P. M. Pathak,A. K. Samantaray,J.-M. Yang,S. W. Kwak 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10
This paper is an attempt to develop a posture control strategy for quadruped robot. Here, a concept of posture control is proposed, in which, a revolute and prismatic (RP) manipulator with payload at the end is used to control the body orientation. For the said analysis necessary model is developed in the bond graph and efficacy of the proposed strategies is validated through simulation results of the developed model.
Singh, V.,Sivaramaiah, G.,Rao, J. L.,Singh, N.,Mohapatra, M.,Singh, P. K.,Pathak, M. S.,Dhoble, S. J. Minerals, Metals & Materials Society and the Insti 2017 Journal of Electronic Materials Vol. No.
<P>LiAl5O8 doped with Fe was synthesized by a propellant combustion route at furnace temperature of 773 K. The phosphor was characterized using powder x-ray diffraction, optical absorption, electron paramagnetic resonance (EPR) and photoluminescence spectroscopic techniques. The optical absorption spectrum exhibits a broad band at 242 nm characteristic of charge transfer between Fe3+-O2-. On excitation with 293 nm, emission band for the Fe3+ ion was observed at 687 nm. The CIE (International Commission on Illumination or Commission Internationale de l'Elcairage) coordinates for the system were evaluated adopting standard procedure which suggested that the system can be effective as a deep red emitting phosphor. The EPR spectrum of this phosphor exhibits a number of resonance signals characteristic of Fe3+ ions. The resonance signals at g = 3.16, 2.27 are attributed to Fe3+ present at tetrahedral site with an axial symmetry. The resonance signals at g = 1.98 and 1.43 are attributed to Fe3+ ions in octahedral site with an axial symmetry. Various EPR parameters such as the number of spins, Gibbs free energy, magnetic susceptibility, Curie constant and effective magnetic moment values are calculated and compared at room temperature and 110 K.</P>
Prevalence of Phytophthora Blight of Pigeonpea in the Deccan Plateau of India
M. Sharma,S. Pande,M. Pathak,J. Narayana Rao,P. Anil Kumar,D. Madhusudan Reddy,V. I. Benagi,D. M. Mahalinga,K. K. Zhote,P. N. Karanjkar,B. S. Eksinghe 한국식물병리학회 2006 Plant Pathology Journal Vol.22 No.4
drechsleri f. sp. cajani is the third potentially important disease of pigeonpea in the Deccan Plateau (DP) of India after wilt and sterility mosaic. In the rainy-season of 2005, an outbreak of PB was seen throughout DP. To quantify the incidence and spread of the disease, a systematic survey was conducted in the major pigeonpea growing regions of DP during the crop season 2005. Attempts were made to determine the effect of cropping systems on the PB development and identify resistant cultivars, if any, grown by farmers and on research farms. Widespread incidence of PB was recorded on improved, and or local cultivars grown in different intercropping systems. Majority of improved cultivars grown at research farms were found susceptible to PB (>10% disease incidence). Pigeonpea intercropped with groundnut, black gram and coriander had less disease incidence (≤10%). Three wilt and SM resistant pigeonpea cultivars KPL 96053, ICPL 99044, and ICPL 93179 were found resistant (<10%) to PB as well. However, their resistance to PB needs confirmation under optimum disease development environments.
Cr3+-Doped Yb3Ga5O12 Nanophosphor: Synthesis, Optical, EPR, Studies
Singh, V.,Sivaramaiah, G.,Rao, J. L.,Singh, N.,Pathak, M. S.,Jirimali, H. D.,Singh, P. K.,Srivastava, A. K.,Dhoble, S. J.,Mohapatra, M. Springer Science + Business Media 2016 Journal of electronic materials Vol.45 No.8
<P>Gallium garnets of lanthanides are multifunctional materials especially known for their complicated structure and magnetic properties. In addition, with a suitable transition metal dopant ion, these matrices have been proved to be excellent materials for lasers. In particular, gallium garnet of ytterbium (Yb3Ga5O12) is known to possess excellent properties with regards to these applications. In this connection, Yb3Ga5O12 doped with Cr3+ nanophosphors were synthesized by a solution combustion route. The synthesized material was characterized by powder x-ray diffraction and scanning electron microscopy for phase purity and homogenous morphology. In order to ascertain the oxidation state of the doped ion, diffuse reflectance (DRF), photoluminescence (PL) and electron paramagnetic resonance (EPR) experiments were performed on the sample. The DRF and PL data suggested the stabilisation of the trivalent Cr ion in the matrix. The EPR spectra exhibited two resonance signals with effective g values at g approximate to 7.6 and 4. The EPR data corroborated the DRF and PL results, suggesting the stabilisation of Cr3+ in the matrix at octahedral-type geometries.</P>
Singh, N.,Singh, V.,Sivaramaiah, G.,Rao, J.L.,Singh, P.K.,Pathak, M.S.,Dhoble, S.J.,Mohapatra, M. Elsevier [etc.] 2016 Journal of luminescence Vol.178 No.-
<P>Strong blue-green light emitting MgSrAl10O17:Eu2+,Mn2+ phosphor was synthesized by a low temperature initiated, self-propagating and gas producing combustion process in a very short time (< 5 min). Structural characterization of the luminescent material was studied with X-ray diffraction analysis and energy-dispersive X-ray analysis. The absorption spectrum exhibits bands due to Eu2+ and Mn3+ ions. The excitation spectrum shows a peak at 337 nm. Upon excitation at 337 nm, the emission spectrum exhibits an intense band centered at 462 nm due to transitions from the 4f(6)5d(1) to the 4f(7) configuration of the Eu2+ ions, whereas sharp peak at 513 nm attributed to T-4(1) -> (6)A(1) transition of Mn2+ ions. The X-band EPR spectra of MgSrAl10O17:Eu2+,Mn2+ showed the presence of Eu2+ and Mn2+ ions. (C) 2016 Elsevier B.V. All rights reserved.</P>
Control of compliant legged quadruped robots in the workspace
Gor, M M,Pathak, P M,Samantaray, A K,Yang, J-M,Kwak, S W SAGE Publications 2015 Simulation Vol.91 No.2
<P>Locomotion control of a quadruped robot requires a well-defined gait pattern (i.e., a coordinated actuation of its four legs in some particular fashion with respect to time). It is of practical importance to move the leg tips in a desired trajectory in order to achieve specific objectives such as to avoid obstacles, minimize energy consumption and locomotion time. Along with body displacement, body orientation is an equally important limit parameter during each leg step of the gait pattern. There are several possible gait patterns that maintain stable and aesthetically pleasing locomotion, and most of these are biologically inspired. This article presents quadruped locomotion control in the workspace through a novel control scheme in which the leg forward motion is controlled in the workspace while the body forward motion is controlled by providing the required effort directly to the joint actuators. In this control approach, the leg tip trajectory error drives a proportional-integral controller that is then transformed through the Jacobian to generate the corrective joint torques. For the body forward motion, leg motion is arrested and the joints are provided with opposite motion, which are controlled by a proportional-integral-derivative controller. The proposed method is simple and easy to implement in the workspace. The performance of the proposed control scheme is evaluated through simulations and animations.</P>
Prevalence of Phytophthora Blight of Pigeonpea in the Deccan Plateau of India
Sharma, M.,Pande, S.,Pathak, M.,Rao, J. Narayana,Kumar, P. Anil,Reddy, D. Madhusudan,Benagi, V.I.,Mahalinga, D.M.,Zhote, K.K.,Karanjkar, P.N.,Eksinghe, B.S. The Korean Society of Plant Pathology 2006 Plant Pathology Journal Vol.22 No.4
Phytophthora blight(PB), caused by Phytophthora drechsleri f. sp. cajani is the third potentially important disease of pigeonpea in the Deccan Plateau(DP) of India after wilt and sterility mosaic. In the rainy-season of 2005, an outbreak of PB was seen throughout DP. To quantify the incidence and spread of the disease, a systematic survey was conducted in the major pigeonpea growing regions of DP during the crop season 2005. Attempts were made to determine the effect of cropping systems on the PB development and identify resistant cultivars, if any, grown by farmers and on research farms. Widespread incidence of PB was recorded on improved, and or local cultivars grown in different intercropping systems. Majority of improved cultivars grown at research farms were found susceptible to PB(>10% disease incidence). Pigeonpea intercropped with groundnut, black gram and coriander had less disease incidence(${\leq}10%$). Three wilt and SM resistant pigeonpea cultivars KPL 96053, ICPL 99044, and ICPL 93179 were found resistant(<10%) to PB as well. However, their resistance to PB needs confirmation under optimum disease development environments.