Journal of Ultra Scientist of Physical Sciences - B
Voulume: 29
Issue: 11
Article No. 1
Mechanoluminescence studies of 0.5BaO.0.5ZnO-Al2O3:xEu (x=0,0.02,0.05,0.1,0.2,0.3,0.4,0.5) Phosphor by impulsive deformation technique
Post Graduate Department of Physics, Mahatma Gandhi College, Thiruvananthapuram, Kerala, India - 695004
Post Graduate Department of Physics, Mahatma Gandhi College, Thiruvananthapuram, Kerala, India - 695004
Department of Physics, All Saints College, Thiruvananthapuram, Kerala, India- 695007
Abstract :

The undoped and Eu doped 0.5BaO.0.5 ZnO-Al2O3: xEu phosphors were prepared by the method of high temperature solid state reaction in air atmosphere. The phase formations of the samples were confirmed by taking powder XRD. Monoclinic phases of barium zinc oxides were identified. The mechanoluminescence (ML) studies of the samples were carried out via impulsive deformation technique (impact method). The ML emissions observed during the deformation of samples consist of two peaks such that intensity of second peak is relatively lower than the first. A large difference in ML decay timings were observed in undoped and Eu doped samples. Significant increase in ML intensities were observed due to Eu doping up to 0.3mole % and beyond that concentration of Eu the ML emission intensity decreases considerably. The decay constant of 0.5BaO.0.5 ZnO-Al2O3:0.3Eu is fairly good and also the sample showed a linear rise in intensity with impact velocity. All these suggest the suitability of the sample for stress sensing applications.

Keyword : XRD, doping, mechanoluminescence (ML)
Paper Download Count : 439
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Article No. 2
Unsteady Casson Fluid Flow over Stretching Sheet through Porous Medium with Heat Generation and Viscous Dissipation
Department of Information Technology, Higher College of Technology, Muscat, (Oman)
H&S, Sree Vidyanikethan Engineering College, A. Rangampet, Tirupati (India)
Department of Engineering, Higher College of Technology, Muscat (Oman)
Department of Information Technology, Higher College of Technology, Muscat, (Oman)
Department of Mathematics, S.V.University, Tirupati (India)
Abstract :

In this paper, an unsteady magnetohydrodynamic (MHD) natural convection heat transfer flow of electrically conductive non-Newtonian Casson fluid over a stretching sheet through vertical porous plate with an influence of heat generation and viscous dissipation is investigated. Similarity transformations are employed to transform the governing partial differential equations into ordinary differential equations. The transformed equations are then solved numerically by Runge-Kutta and shooting methods. The heat flow characteristics for different values of the parameters namely Casson fluid parameter, unsteadiness parameter, Eckert number, heat generation parameter, permeability porous parameter and Prandtl number are studied and discussed in detail. The increase of permeability porous parameter reduces the velocity field and enhances the fluid temperature. The heat generation source leads to an increase in thermal boundary layer thickness. The higher viscous dissipative heat causes an increase in the fluid temperature.

Keyword : Casson fluid, Unsteady MHD, Stretching sheet with porous medium, Heat generation, Viscous dissipation
Paper Download Count : 380
View Count : 598
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Article No. 3
Distribution of Uranium in Drinking water and Associated Age-Dependent Radiation Dose in Porakad, Allapuzha District
Center for Advanced Research in Physical Sciences, Department of Physics, Fatima Mata National College (Autonomous), Kollam, (India
bMG College, Thiruvananthapuram
aCenter for Advanced Research in Physical Sciences, Department of Physics, Fatima Mata National College (Autonomous), Kollam, (India)
Abstract :

Exposure due to natural radiation is of particular importance because it accounts for the largest contribution (nearly 85 %) to the total collective dose of the world population. Uranium is a heavy metal that is not only radiologically harmful but also a well-known nephrotoxic element. In the present study, about 30 water samples were collected from open-wells ,Bore well and supplied water from taps, from the coastal region of Porakad, Allapuzha District. The Uranium concentration in the water samples was analyzed by light-emitting diode (LED)-based Ultraviolet (UV) fluorimeter (Quantalase Enterprises Pvt. Ltd, Indore, Madhya Pradesh, India). The associated age dependent Uranium intake was estimated by taking the prescribed water intake values. Most of the water samples had the Uranium concentration below the standards set by United States Environmental Protection Agency (30 ppb).

Keyword : Ultraviolet fluorimeter, Quantalase,Age-Dependent dose
Paper Download Count : 412
View Count : 531
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Article No. 4
Relationship between speed of Full Halo Coronal Mass Ejections and Cosmic ray intensity
Department of Physics, Govt. Model Science College, Rewa (M.P.) 486001 (India)
Department of Physics, Govt. College, Katangi, Distt. Balaghat (M.P.) 481445 (India)
Department of Physics, Govt. JST P.G. College, Balaghat (M.P.) 481001 (India)
Abstract :

Halo and Full Halo CMEs (Coronal Mass Ejections) events observed by Solar and Heliospheric observatory (SOHO) mission are used to study their effects on cosmic ray intensity variations during 2009 to 2012, which correspond to ascending phase of recent solar cycle 24. It is found that the speed of HCMEs (Halo Coronal Mass Ejections) are significantly negative correlated with cosmic ray intensity. All the FHCMEs (Full Halo Coronal Mass Ejections) having the linear speed  1000 km/s produce transient decrease in cosmic ray intensity on short-term basis. The results of analysis indicated that the magnitude of decrease in cosmic ray intensity is large for high speed FHCMEs (Full Halo Coronal Mass Ejections) in comparison with low speed FHCMEs (Full Halo Coronal Mass Ejections).

Keyword : Full Halo Coronal Mass Ejection, Cosmic rays, Transient decrease, Solar activity, PACS Nos. 96.50S; 96.60 ph; 96.50Wx
Paper Download Count : 585
View Count : 552
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Article No. 5
Near field non-ionising electromagnetic radiation of cellular base stations in selected locations
Department of Physics, Fatima Mata National College(Autonomous), Kollam-691001, (India)
Department of Applied Physics, The Papua New Guinea University of Technology, Lae, (Papua New Guinea)
Abstract :

Cellular phone technology has made radical changes in global telecommunication scenario with exponential growth in cell phones and base towers. The effect of non-ionizing electromagnetic radiations on human health is a subject of serious concern with the enormous installation of base stations. With a view to study the near field areas of base stations, we selected certain locations in southern districts of Kollam and Trivandrum in Kerala state, India. We assessed the power density of radio frequency waves from mobile towers using a handheld pocket digital LCD microwave leakage radiation detector. The area near the mobile towers were divided into concentric circles, each with increasing radii of 5m maximum. The survey was carried out in various towns having large population. The power density and Specific Absorption Rate (SAR) rates were determined from the field measurements. The present study was conducted only to near field and ground level radiations.

Keyword : tower radiation, exposure, near field radiation, SAR
Paper Download Count : 424
View Count : 558
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