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Search Results: 1 - 10 of 138839 matches for " K. Raghunath "
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Embodied Energy & Cost Issues of Tank-Bed-Lime Based Geopolymer Adobes  [PDF]
T. K. Jyothi, B. N. Varsha, S. Raghunath, K. S. Jagadish
Open Journal of Energy Efficiency (OJEE) , 2017, DOI: 10.4236/ojee.2017.63010
Abstract: It is well-known that a product or a system is sustainable if it is economically viable, socially acceptable and environmentally friendly. Load bearing masonry is one such example which is quite sustainable, especially if the masonry units are locally available. It is important to quantify the environmental benefits and cost, if an alternative to an existing technology is to be suggested. Of course the issues related to acceptance have to be discussed and addressed. This paper presents the quantification of embodied energy and cost of lime-pozzolana-cement (LPC) geopolymer based masonry units made using locally available bulk ingredients viz. tank-bed soil (TBS) and brick-powder (BP). The masonry adobe units developed have achieved the target performance in terms of strength, low water absorption and relative ease of production. Simultaneously the issues related to cost are also discussed in this paper. The studies have revealed that the bulk contributor to embodied energy and cost of geopolymer adobes are the alkaline materials viz sodium hydroxide and sodium silicate. However, the embodied energy and cost per unit strength appears to be better than that of conventional table moulded bricks in south India, especially when alkaline solution at 2M concentration is used with LPC.
An investigation of hot deformation response of particulate-reinforced magnesium + 4.5% titanium composite
Raghunath, B. K.;Karthikeyan, R.;Gupta, M.;
Materials Research , 2006, DOI: 10.1590/S1516-14392006000200019
Abstract: the deformation response of magnesium based metal matrix composite was investigated by means of hot compression tests. the flow curves were obtained in the temperature and strain rate range of 300-500 °c and 0.001-1 s-1 respectively in order to obtain the processing maps of the studied material and interpreting them on the basis of the dynamic material model. micro-structural characterization studies conducted on the deformed composite samples, using optical and scanning electron microscopy, revealed a recrystallized grain morphology, debonding of titanium particles, particle breakage and cracking of the matrix. the observations were performed in order to describe the behavior of the material under hot forming operation in terms of material damage and micro- structural modification.
Rayleigh lidar observations of enhanced stratopause temperature over Gadanki (13.5° N, 79.2° E) during major stratospheric warming in 2006
S. Sridharan, S. Sathishkumar,K. Raghunath
Annales Geophysicae (ANGEO) , 2009,
Abstract: Rayleigh lidar observations of temperature structure and gravity wave activity were carried out at Gadanki (13.5° N, 79.2° E) during January–February 2006. A major stratospheric warming event occurred at high latitude during the end of January and early February. There was a sudden enhancement in the stratopause temperature over Gadanki coinciding with the date of onset of the major stratospheric warming event which occurred at high latitudes. The temperature enhancement persisted even after the end of the high latitude major warming event. During the same time, the UKMO (United Kingdom Meteorological Office) zonal mean temperature showed a similar warming episode at 10° N and cooling episode at 60° N around the region of stratopause. This could be due to ascending (descending) motions at high (low) latitudes above the critical level of planetary waves, where there was no planetary wave flux. The time variation of the gravity wave potential energy computed from the temperature perturbations over Gadanki shows variabilities at planetary wave periods, suggesting a non-linear interaction between gravity waves and planetary waves. The space-time analysis of UKMO temperature data at high and low latitudes shows the presence of similar periodicities of planetary wave of zonal wavenumber 1.
Bacterial Load and Diversity in Portunus pelagicus (Crustacea, Decapoda, Portunidae) Larvae and Rearing Media
Raghunath Ravi,K.S. Sobhana,Mary K. Manisseri
Journal of Aquaculture Feed Science and Nutrition , 2012, DOI: 10.3923/joafsnu.2011.1.7
Abstract: A study was conducted to estimate the bacterial load as well as diversity in the larvae and rearing system of the marine blue swimmer crab Portunus pelagicus. Berried females of mean carapace width 159.86±3.04 mm were collected from the wild and the zoeae from a single brood were used for the investigation. The bacterial load in the filtered seawater, rearing seawater, live and dead larval tissue were estimated and the bacterial species diversity was identified following standard identification keys based on the morphological, phenotypic as well as biochemical characteristics of the colonies isolated on Trypticase Soy Agar (TSA) and Thiosulphate Citrate Bilesalt Sucrose agar (TCBS). The bacterial loads recorded were 1.2x104, 2.9x105 CFU mL-1, 2.3x105 and 4.8x107 CFU g-1 for filtered seawater, rearing seawater, live larvae and dead larvae, respectively. The dominant bacterial strains identified were Vibrio vulnificus and Vibrio alginolyticus in rearing seawater; Pseudomonas alcaligenes, Pseudomonas acidovorans, Bacillus marinus and Alcaligenes sp. in live larval tissue homogenate and Vibrio splendidus, V. vulnificus, V. alginolyticus and Vibrio parahaemolyticus in dead larval tissue homogenate. No growth was observed on TSA and TCBS plates inoculated with filtered seawater.
DEVELOPMENT OF CALIBRATION SCHEME AND SOFTWARE FOR DOPPLER LIDAR RECEIVER
K RAGHUNATH,DV ABHINAVA KARTHIK,S NARAYANA REDDY,K RAMESH
International Journal of Engineering Science and Technology , 2011,
Abstract: An Incoherent Doppler lidar (laser radar) is being developed at National Atmospheric Research Laboratory,Gadanki(13.5oN, 79.2oE), India to measure winds in troposphere and stratosphere. The lidar has a stabilised laser source, a telescope and a receiver. In the receive chain, the system employs a servo stabilised Fabry-Pérot Interferometer as a narrow pasband filter for measuring wind velocities. Calibration of receive chain with Fabry-Perot Interferometer is crucial for deriving the wind velocities. The developed calibration scheme gives two informations, one, the exact operation point of the Fabry-Pérot Interferometer and the second to generate “Lookup table” which is useful in deducing the winds. A software is developed for the purpose which is tested independently.
Constituent Quark Scaling of Strangeness Enhancement in Heavy-Ion Collisions
Nirbhay K. Behera,Raghunath Sahoo,Basanta K. Nandi
Advances in High Energy Physics , 2013, DOI: 10.1155/2013/273248
Abstract: In the framework of a nuclear overlap model, we estimate the number of nucleons and quark participants in proton-proton, proton-nucleus, and nucleus-nucleus collisions. We observe the number of nucleon- ( -) normalized enhancement of multistrange particles, which shows a monotonic increase with centrality and turns out to be a centrality-independent scaling behavior when normalized to number of constituent quarks participating in the collision ( ). In addition, we observe that the -normalized enhancement, when further normalized to the strangeness content, shows a strangeness-independent scaling behavior. This holds good at top RHIC energy. However, the corresponding SPS data show a weak -scaling. Moreover, the strangeness scaling seems to be violated at top SPS energy. This scaling at RHIC indicates that the partonic degrees of freedom play an important role in the production of multistrange particles. Top SPS energy, in view of the above observations, shows a coexistence of hadronic and partonic phases. Therefore we give a comparison of data with HIJING, AMPT, and UrQMD models to understand the particle production dynamics at different energies. 1. Introduction Relativistic heavy-ion collisions aim at creating matter at extreme conditions of energy density and temperature, which is governed by the partonic degrees of freedom called quark-gluon plasma (QGP) [1]. The main focus of these studies is the observation of quark-hadron phase transition and exploration of quantum chromodynamics (QCD) phase diagram [2]. In the early phases of ultrarelativistic heavy-ion collisions, when a hot and dense region is formed at the core of the reaction zone, different quark flavors are produced. Then, the produced matter undergoes transverse expansion and multiple scattering among the produced particles. The formation of the hadrons from the partonic phase is accomplished through further expansion and cooling of the system. In proton-proton ( ) collisions, the formation of QGP is not expected, whereas a possible formation of QGP is expected in nucleus-nucleus collisions [3, 4]. Hence, a comparative study of produced particles in collisions, with that of collisions, could give better understanding of the properties of the medium formed in collisions. In the midrapidity region, strangeness enhancement has been proposed as a potential signature of QGP [5, 6]. Strange baryons are produced in strong interaction processes, and decay through weak interaction. It has been observed that multistrange baryons, that is, , , and , are formed and decoupled from the system earlier
Antioxidant and Phenolic Content of Nuts, Oil Seeds, Milk and Milk Products Commonly Consumed in India  [PDF]
Dande Sreeramulu, Manchala Raghunath
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.25059
Abstract: Food provides not only essential nutrients required for life, but also bioactive compounds usefull to maintan good health and disease prevention. Abundant epidemiological evidences suggest that consumption of food rich in antioxi-dants (non-nutritional components) can prevent degenerative diseases. A total of 26 commonly consumed nuts, oil seeds, edible oils, milk and milk products were chosen for the study. Considering the fact that antioxidant content (AOC) and phenolic contents (PC) of these foods was not established systematically in Indian context. Therefore, we have assessed and correlated the AOC and PC, an important antioxidant constituents of plant foods. AOC was assessed by DPPH (2, 2-Diphenyl-1-picryl hydrazyl) scavenging activity and FRAP (Ferric reducing antioxidant power) methods and phenolic content (PC), using Folin-Ciocalteu reagent. Among the nuts and oil seeds arecanut had the highest phenolic and antioxidant content 10841, 4220341 mg/100g respectively. In milk, edible oils and sugars the values ranged from 336 -11674 mg/100g. Jaggery had the highest PC and AOC among the foods studied . Although AOC and PC showed wide variation among the foods, AOC was correlated significantly with PC. Indeed the ‘r’ value between PC and AOC (DPPH and FRAP) was 0.99 (p < 0.01) among the nuts and oil seeds, while in milk, milk products and sugars, the “r” values ranged from 0.93 and 0.99 (p < 0.01) respectively. The overall results indicate that the phenolic compounds may be significant contributors to the AOC of the foods studied.
A new method to derive middle atmospheric temperature profiles using a combination of Rayleigh lidar and O2 airglow temperatures measurements
A. Taori, A. Jayaraman, K. Raghunath,V. Kamalakar
Annales Geophysicae (ANGEO) , 2012,
Abstract: The vertical temperature profiles in a typical Rayleigh lidar system depends on the backscatter photon counts and the CIRA-86 model inputs. For the first time, we show that, by making simultaneous measurements of Rayleigh lidar and upper mesospheric O2 temperatures, the lidar capability can be enhanced to obtain mesospheric temperature profile up to about 95 km altitudes. The obtained results are compared with instantaneous space-borne SABER measurements for a validation.
21 cm signal from cosmic dawn: Imprints of spin temperature fluctuations and peculiar velocities
Raghunath Ghara,T. Roy Choudhury,Kanan K. Datta
Physics , 2014, DOI: 10.1093/mnras/stu2512
Abstract: The 21 cm brightness temperature $\delta T_{\rm b}$ fluctuations from reionization promise to provide information on the physical processes during that epoch. We present a formalism for generating the $\delta T_{\rm b}$ distribution using dark matter simulations and an one-dimensional radiative transfer code. Our analysis is able to account for the spin temperature $T_{\rm S}$ fluctuations arising from inhomogeneous X-ray heating and Ly$\alpha$ coupling during cosmic dawn. The $\delta T_{\rm b}$ power spectrum amplitude at large scales ($k \sim 0.1$ Mpc$^{-1}$) is maximum when $\sim 10\%$ of the gas (by volume) is heated above the CMB temperature. The power spectrum shows a "bump"-like feature during cosmic dawn and its location measures the typical sizes of heated regions. We find that the effect of peculiar velocities on the power spectrum is negligible at large scales for most part of the reionization history. During early stages (when the volume averaged ionization fraction $\lesssim 0.2$) this is because the signal is dominated by fluctuations in $T_{\rm S}$. For reionization models that are solely driven by stars within high mass ($\gtrsim 10^9\, \rm M_{\odot}$) haloes, the peculiar velocity effects are prominent only at smaller scales ($k \gtrsim 0.4$ Mpc$^{-1}$) where patchiness in the neutral hydrogen density dominates the signal. The conclusions are unaffected by changes in the amplitude or steepness in the X-ray spectra of the sources.
Essentials of Microbiology by Anuradha De. National Series
Raghunath D
Indian Journal of Medical Microbiology , 2010,
Abstract:
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