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- 저자 : Firoz, Kazi A. (검색결과 56 건)
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Correlation Between Reflectance and Photoluminescent Properties of Al-rich ZnO Nano-Structures
Firoz Khan,백성호,Nafis Ahmad,이건희,서태훈,서은경,김재현 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.3
Al rich zinc oxide nano-structured films were synthesized using spin coating sol-gel technique. The films were annealed in oxygen ambient in the temperature range of 200-700 °C. The structural, optical, and photoluminescence (PL) properties of the films were studied at various annealing temperatures using X-ray diffraction spectroscopy, field emission scanning electron microscopy, photoluminescence emission spectra measurement, and Raman and UV-Vis spectroscopy. The optical band gap was found to decrease with the increase of the annealing temperature following the Gauss Amp function due to the confinement of the exciton. The PL peak intensity in the near band region (INBE) was found to increase with the increase of the annealing temperature up to 600 °C, then to decrease fast to a lower value for the annealing temperature of 700 °C due to crystalline quality. The Raman peak of E2 (low) was red shifted from 118 cm-1 to 126 cm-1 with the increase of the annealing temperature. The intensity of the second order phonon (TA+LO) at 674 cm-1 was found to decrease with the increase of the annealing temperature. The normalized values of the reflectance and the PL intensity in the NBE region were highest for the annealing temperature of 600 °C. A special correlation was found between the reflectance at λ = 1000 nm and the normalized PL intensity in the green region due to scattering due to presence of grains.
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Firoz Ahmad,Md Meraj Uddin,Laxmi Goparaju 대한공간정보학회 2018 Spatial Information Research Vol.26 No.5
In view of climate change scenario, the increasing population, higher food demand and deteriorating land productivity are the key issues which need to be addressed in present time frame because it will be more critical in the future. The scientific evaluation of land for agroforestry is a step towards sustainability for achieving the socio-economic and environmental goal of the community. The objective of the present study was to investigate the suitability of land use/land cover of Lohardaga district of state of Jharkhand, India for agroforestry use based on FAO land suitability criteria utilizing Landsat-8 images (NDVI/wetness), ASTER DEM (elevation/slope/ drainage and watershed), ancillary data source (rainfall/ organic carbon/pH and nutrient status). The analysis of our study for agroforestry suitability reveals that 50.5% area as highly suitable (S1), 28.2% area as moderately suitable (S2), 20% area as marginally suitable (S3) and 1.3% area as not suitable (NS). Only 2.9% of the total land area is dominated by two season crop which is a matter of serious concern. The statistical analysis of the results reveals that the lands have huge potentiality for harnessing agroforestry crops if utilized scientifically. Such results will greatly help to the state level policymakers for achieving the national agroforestry policy goal for extending it to the new areas in the districts of Jharkhand.
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Firoz Ahmad,Laxmi Goparaju 대한공간정보학회 2018 Spatial Information Research Vol.26 No.6
The dynamic changes of forest fire events are due to the swing of climate parameter. Geospatial technology has strong capability to analyze various thematic datasets towards visualization of spatial/temporal pattern and plays a vital role in fire management efforts. This paper aims to analyze the climate and forest fire trend using Geospatial technology in the state of Orissa of India. The 84.5% of forest fire events are observed in the month of March and April and it is significantly high in the south of Kandhamal, east of Kalahandi, north of Rayagada and north of Gajapati district. The parameters which favour the forest fire events in the month of March onwards were observed. The Maximum temperature is showing an increasing trend from February to June whereas the increase is significantly high during March and April. The solar radiation increased to 144% in the month of March when compared with preceding month whereas relative humidity was decreased to 64% in the same month. The evaluation of Cramer V coefficient values of minimum temperature, solar radiation, maximum temperature and relative humidity are found to be 0.302, 0.327, 0.366 and 0.482 respectively. The relative humidity shows strong relationship with fire events. Such data analysis would help in safeguarding the forest.
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AN INTERPRETATION OF THE POSSIBLE MECHANISMS OF TWO GROUND-LEVEL ENHANCEMENT EVENTS
Firoz, Kazi A.,Gan, W. Q.,Moon, Y.-J.,LI, C. IOP Publishing 2012 The Astrophysical journal Vol.758 No.2
<P>We have carried out this work to clarify the possible mechanisms of two important high-energy particle events (GLE69 2005 January 20, 06: 46 UT and GLE70 2006 December 13, 02: 45 UT). For this purpose, the cosmic-ray intensities registered by neutron monitors at several sites have been analyzed and studied with concurrent solar flares of different energy bands. To determine whether the ground-level enhancement (GLE) might be caused by the energy released from a solar flare or a CME-driven shock, we identify the particle injection time in terms of the lowest value of the spectral indices deduced from proton fluxes. If the GLE is caused by the energy released from particle acceleration in a solar flare, the intensive phase of the flare representing extreme emission should lie within the injection time. While fulfilling this criterion, it is further necessary to understand the possible relativistic energy computed in terms of the possible travel time deduced by employing the observational time lag between the GLE and the concurrent solar flare. Accordingly, we have found that GLE69 is procured with sufficient possible relativistic energy (similar to 1.619 GeV) by the energy released from particle accelerations in the intensive phases of a solar flare components that have been corroborated by the injection time. The intensive phases of the flare components have also been justified with the prominent phases of a solar radio type III burst. For event GLE70, the particle injection time lies within the CME-driven shock justified by a solar radio type II burst which seems to be capable of procuring sufficient possible relativistic energies (similar to 1.231 to similar to 2.017 GeV). It is also noted that any fractional amount of energy (similar to 0.226 to similar to 0.694 GeV) from preceding flare components might be considered as a contribution to the shock acceleration process. Thus, GLE70 is presumably caused by the sum of the energy released mostly from a CME-driven shock and partially from preceding flare components.</P>
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Effect of Al Concentration on Photoluminescence Properties of Sol-Gel Derived Hydrogen Annealed ZnO
Firoz Khan,Sadia Ameen,Minwu Song,Mushahid Husain,Abdul Mobin,Hyung-Shik Shin 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.2
The effect of the Al/Zn atomic ratio on the photoluminescence properties of hydrogen annealed undoped and Al rich ZnO (AZO) films was studied. The Al/Zn atomic ratios in the AZO films were varied from 0to 40%. All the AZO films exhibited three peaks in the UV, green and red regions, whereas the undoped ZnO films had two peaks in the UV and green regions. The PL intensity in the UV and red regions increased with an increase in Al concentrations. The highest PL intensity in the UV region was observed in the 20% Al/Zn atomic ratio due to improvement in crystal quality which was also confirmed by XRD measurements. The PL emission in the red region was due to complex luminescent centers like (Vzn-Alzn)−. A blue shift was seen in the red region with the introduction of Al. The 20% AZO films obtained the strongest signal at ~420 cm−1, whereas no FTIR signal was observed at 420 cm−1 in undoped ZnO. The bond signature at ~420 cm−1 might be responsible for the highest PL intensity in NBE and red regions.
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ON THE POSSIBLE MECHANISMS OF TWO GROUND-LEVEL ENHANCEMENT EVENTS
Firoz, Kazi A.,Moon, Y.-J.,Park, S.-H.,Kudela, K.,Islam, Jamal N.,Dorman, Lev I. IOP Publishing 2011 The Astrophysical journal Vol.743 No.2
<P>We have carried out a case study on the possible mechanism of ground-level enhancement (GLE) occurrence. For this, we have considered two GLE events (GLE69 and GLE70) and scrutinized their relationships with simultaneous soft/hard X-rays as well as solar energetic particle (SEP) fluxes of different energy bands. Although most of the energy bands of the flares maintain strong correlations (r >= 0.8) with the GLEs, depending only on this evidence we could not precisely imply that GLEs can be caused by solar flares. So, we have attempted to understand possible relativistic energies of the GLEs, which have been determined by availing the relativistic traversing time and velocities of the particles along the nominal path of Archimedean spiral magnetic field lines. Results suggest that the energy released from accelerated particles in high-energy (gamma-ray) solar flares might sometimes cause the GLE. We found that during hard X-ray flares <= 7MeV, the relativistic energy (<= 0.23 GeV) of GLE69 was much less than 1 GeV whereas during SEP flares >30 MeV the possible relativistic energy of GLE69 amounts to similar to 2.78 GeV, and this makes us believe that GLE69 might be caused by the energy released from particle accelerations in high-energy solar flares. On the contrary, during hard X-ray (<= 7 MeV) as well as gamma-ray solar flares (>30 MeV) the relativistic energy of GLE70 amounts to <=similar to 0.35 GeV, indicating that the GLE70 was presumably not caused by the released energy from accelerated particles in the solar flare. Alternatively, the released energy from particle accelerations in solar radio emission type II burst concomitant coronal-mass-ejection-driven shocks seems to have been responsible for causing the GLE70.</P>
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Firoz Ahmad,Md Meraj Uddin,Laxmi Goparaju 대한공간정보학회 2019 Spatial Information Research Vol.27 No.4
The present study examined the relationship among various diversified datasets using remote sensing and GIS. About 72% of the total forest area of Chhattisgarh state (59,935 km2) has shown a trend of negative change between the periods (1982 and 2006). Around 50% of the total forest fires of the state were found in the two tehsils of Narayanpur and Bijapur with two major forest fire hotspots. Approximately 86% of the total forest fire event of the state occurred in the category of ‘‘tropical mixed deciduous and dry deciduous forests’’ whereas the intensity of forest fire events was found 2.2 times in the category ‘‘tropical lowland forests, broadleaved, evergreen,\ 1000 m’’ when it was compared with the category of ‘‘tropical mixed deciduous and dry deciduous forests.’’ The highest poverty percent was found in the tehsil of Bijapur (65.9%) which retains a significantly high percentage of the tribal population (73.1%). The adaptive capacity of Raipur tehsil (state capital) is high whereas it reduces significantly towards north and south from the state capital. The climate anomaly data evaluation for the year 2030 showed variation such as reduction in rainfall and increase in temperature will significantly maneuver the forest fire regime in future is a matter of serious concern. The outcomes of the present study would certainly guide the policymakers of the state of Chhattisgarh to prepare a meaningful, transparent and robust plan for the betterment of people keeping in mind of future climate change impact.
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