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Bhatt B.,P.A. College | Prasad L.,P.A. College | Chandra H.,Mmm University Of Technology | Garia S.,P.A. College
Astrophysics and Space Science | Year: 2016

We have statistically studied 220 events from 1996 to 2008 (i.e. solar cycle 23). Two set of flare-CME is examined one with Deca-hectometric (DH) type II and other without DH type II radio burst. Out of 220 events 135 (flare-halo CME) are accompanied with DH type II radio burst and 85 are without DH type II radio burst. Statistical analysis is performed to examine the distribution of solar flare-halo CME around the solar disk and to investigate the relationship between solar flare and halo CME parameters in case of with and without DH type II radio burst. In our analysis we have observed that: (i) 10–20° latitudinal belt is more effective than the other belts for DH type II and without DH type II radio burst. In this belt, the southern region is more effective in case of DH type II radio burst, whereas in case of without DH type II radio burst dominance exits in the northern region. (ii) 0–10° longitudinal belt is more effective than the other belts for DH type II radio burst and without DH type II radio burst. In this belt, the western region is more effective in case of DH type II radio burst, while in case of without DH type II radio burst dominance exits in the eastern region. (iii) Mean speed of halo CMEs (1382 km/s) with DH type II radio burst is more than the mean speed of halo CMEs (775 km/s) without DH type II radio burst. (iv) Maximum number of M-class flares is found in both the cases. (v) Average speed of halo CMEs in each class accompanied with DH type II radio burst is higher than the average speed of halo CMEs in each class without DH type II radio burst. (vi) Average speed of halo CMEs, associated with X-class flares, is greater than the other class of solar flares in both the cases. © 2016, Springer Science+Business Media Dordrecht. Source


Kumar V.,Krishna Institute of Engineering and Technology | Kumar P.,Bharat Institute of Technology | Yadav S.,Bharat Institute of Technology | Kumar V.,Bharat Institute of Technology | And 2 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2015

Tin selenide was synthesized by mechanical alloying method and the films were grown by economic screen-printing method on glass substrate. The source materials used for the preparation of films were tin selenide and stannic chloride. The structural, elemental, morphological, optical and electrical properties of the prepared films were investigated by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), Raman spectroscopy, UV–Vis spectrometry, two point probe method and Hall effect measurement technique. XRD analysis confirms that the films were polycrystalline in nature, exhibiting orthorhombic structure with most prominent orientation of grains along (111) and (112) direction. EDAX analysis indicates that the prepared films were nearly stoichiometric in nature. SEM studies show that smaller grains were assembled to form a bunch of bigger size. Raman spectra were used to observe the characteristic vibrational modes of SnSe. Direct type of transition of band gap was confirmed by reflection spectra occurring at 1.1 eV. The dark electrical conductivity and photoconductivity reveals that the films were semiconducting in behaviour. The carrier type of films was determined by Hall effect measurement. © 2015 Springer Science+Business Media New York Source


Kumar P.,ABES Engineering College | Chauhan R.K.,Mmm University Of Technology | Gupta M.,Krishna Institute of Engineering and Technology
International Conference on Advanced Computing and Communication Technologies, ACCT | Year: 2014

In this paper high frequency small-signal model is presented for optimization of device parameters of SiGe HBT with 0.1μm base-width which is based on the technique of direct parameter extraction. For this purpose, we use process simulator ATHENA and device simulator ATLAS from SILAVCO International. Further, a model is proposed to portray the noise in SiGe HBT with uniform Ge concentration in base. The results of the SiGe HBTs are advanced to those of III-V semiconductor devices. © 2014 IEEE. Source


Dwivedi D.K.,Mmm University Of Technology | Pathak H.P.,Mmm University Of Technology | Kumar V.,Krishna Institute of Engineering and Technology | Shukla N.,Mmm University Of Technology
Advanced Science Letters | Year: 2014

Se66Te25Sb9bulk sample was obtained using conventional melt quenching technique. Thin films of a-Se66Te25Sb9of thickness 400 nm, were prepared by vacuum evaporation technique in a base pressure of 10-6Torr on to well cleaned glass substrate. The thickness of the film was measured using a single crystal thickness monitor. a- Se66Te25Sb9thin films were annealed at different temperatures below its crystallization temperature for 2 h. The structure of as prepared and annealed film has been studied by X-ray diffraction. The X-ray pattern indicates that the as-prepared film is amorphous in nature but it shows some polycrystalline structure in amorphous phases after annealing. The optical band gap of as prepared and annealed film as a function of photon energy in the wavelength range 400–1100 nm has been studied. It has been found that the optical band gap decreases with increasing annealing temperatures in the present system. © 2014 American Scientific Publishers All rights reserved. Source


Pathak H.P.,Mmm University Of Technology | Shukla N.,Mmm University Of Technology | Kumar V.,Krishna Institute of Engineering and Technology | Dwivedi D.K.,Mmm University Of Technology
Optical Materials | Year: 2016

Se75-xTe25Inx (x = 0, 3, 6, & 9) bulk glasses were obtained by melt quench technique. Thin films of thickness 400 nm were prepared by thermal evaporation technique at a base pressure of 10-6 Torr onto well cleaned glass substrate. a-Se75-xTe25Inx thin films were annealed at different temperatures for 2 h. As prepared and annealed films were characterized by X-ray diffraction and UV-Vis spectroscopy. The X-ray diffraction results show that the as-prepared films are of amorphous nature while it shows some poly-crystalline structure in amorphous phases after annealing. The optical absorption spectra of these films were measured in the wavelength range 400-1100 nm in order to derive the extinction and absorption coefficient of these films. It was found that the mechanism of optical absorption follows the rule of allowed non-direct transition. The optical band gap of as prepared and annealed films as a function of photon energy has been studied. The optical band gap is found to decrease with increase in annealing temperature in the present glassy system. It happens due to crystallization of amorphous films. The decrease in optical band gap due to annealing is an interesting behavior for a material to be used in optical storage. The optical band gap has been observed to decrease with the increase of In content in Se-Te glassy system. © 2015 Elsevier B.V. Source

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