16,258 research outputs found

    Analysis of field measurements of carbon dioxide and water vapor fluxes

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    Analysis of the field measurements of carbon dioxide and water vapor fluxes is discussed. These data were examined in conjunction with reflectance obtained from helicopter mounted Modular Multiband Radiometer. These measurements are representative of the canopy scale (10 to 100 m)(exp 2) and provide a good basis for investigating the hypotheses/relationship potentially useful in remote sensing applications. All the micrometeorological data collected during FIFE-89 were processed and fluxes of CO2, water vapor, and sensible heat were calculated. Soil CO2 fluxes were also estimated. Employing these soil CO2 flux values, in conjunction with micrometeorological measurements, canopy photosynthesis is being estimated. A biochemical model of leaf photosynthesis was adapted to the prairie vegetation. The modeled leaf photosynthesis rates were scaled up to the canopy level. This model and a multiplicative stomatal conductance model are also used to calculate canopy conductance

    Analysis of soil and species composition

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    Measurements were made during May to October, 1987 and June to August, 1989 over a tallgrass prairie near Manhattan, Kansas. Soil at the experimental site is predominantly Dwight silty clay loam. The prairie was burned on 16 April 1987 and on 28 April 1989 to improve the mix of grasses and forbs. The experimental area was not grazed during 1986 - 1989. A summary of results are given for soil moisture and plant growth; momentum flux and canopy aerodynamic characteristics; evapotranspiration, components of energy balance and canopy conductance; modeling canopy stomatal conductance; canopy photosynthesis, photosynthetic efficiency and water use efficiency; modeling canopy photosynthesis; the carbon dioxide budget in a temperate grassland ecosystem; and photosynthesis and stomatal conductance related to reflectance on the canopy scale

    Opto-mechanical effects in self-organization of a Bose-Einstein condensate in an optical cavity

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    The influence of mirror motion on the spatial self organization of a Bose-Einstein condensate (BEC) in an optical cavity is studied. We show that the mirror dynamics tends to destroy the process of self organization. An additional external phonon pump is shown to modify the critical photon pump needed to observe the onset of self organization.Comment: 10 pages, 10 figure

    Field theoretic calculation of scalar turbulence

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    The cascade rate of passive scalar and Bachelor's constant in scalar turbulence are calculated using the flux formula. This calculation is done to first order in perturbation series. Batchelor's constant in three dimension is found to be approximately 1.25. In higher dimension, the constant increases as d1/3d^{1/3}.Comment: RevTex4, publ. in Int. J. Mod. Phy. B, v.15, p.3419, 200

    Quark-lepton complementarity model based predictions for θ23PMNS\theta_{23}^{PMNS} with neutrino mass hierarchy

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    After the successful investigation and confirmation of non zero θ13PMNS\theta_{13}^{PMNS} by various experiments, we are standing at a square where we still encounter a number of issues, which are to be settled. In this paper, we have extended our recent work towards a precise prediction of the θ23PMNS\theta_{23}^{PMNS} mixing angle, taking into account the neutrino mass hierarchy. We parameterize the non-trivial correlation between quark (CKM) and lepton (PMNS) mixing matrices in quark-lepton complementarity (QLC) model as Vc=UCKM.ψ.UPMNSV_{c}= U_{CKM}. \psi. U_{PMNS}, where ψ\psi is a diagonal phase matrix. Monte Carlo simulations are used to estimate the texture of VcV_{c} and compare the results with the standard Tri-Bi-Maximal (TBM) and Bi-Maximal(BM) structures of neutrino mixing matrix. We have predicted the value of θ23PMNS\theta_{23}^{PMNS} for normal and inverted neutrino mass hierarchies. The value of θ23PMNS\theta_{23}^{PMNS} obtained for two cases are about 1.3σ1.3\sigma away from each other, implying the better precision can give us a strong hint for the type of neutrino mass hierarchy.Comment: 3 pages, 3 figure

    Inherent properties of binary tetrahedral semiconductors

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    A new approach utilising the concept of ionic charge theory has been used to explain the inherent properties such as lattice thermal conductivity and bulk modulus of 3,5 and 2,6 semiconductors. The lattice thermal conductivity of these semiconductors exhibit a linear relationship when plotted on a log scale against the nearest neighbour distance but fall on two straight lines according to the product of the ionic charge of the compounds. On the basis of this result a simple relationship of lattice thermal conductivity with bulk modulus is proposed and used to estimate the bulk modulus of these semiconductors. A fairly good agreement has been found between the experimantal and calculated values of these parameters for zinc blende structured solids.Comment: 6 pages, 19 reference

    Efficient absolute aspect determination of a balloon borne far infrared telescope using a solid state optical photometer

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    The observational and operational efficiency of the TIFR 1 meter balloon borne far infrared telescope has been improved by incorporating a multielement solid state optical photometer (SSOP) at the Cassegrain focus of the telescope. The SSOP is based on a 1-D linear photo diode array (PDA). The online and offline processing schemes of the PDA signals which have been developed, lead to improvement in the determination of absolute telescope aspect (∼\sim 0\farcm8), which is very crucial for carrying out the observations as well as offline analysis. The SSOP and its performance during a recent balloon flight are presented here.Comment: To appear in the February 2000 issue of the PAS

    Study of Distribution and Asymmetry of Solar Active Prominences During Solar Cycle 23

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    In this paper we present the results of a study of the spatial distribution and asymmetry of solar active prominences (SAP) for the period 1996-2007 (solar cycle 23). For more meaningful statistical analysis we have analysed the distribution and asymmetry of SAP in two subdivisions viz. Group1 (ADF, APR, DSF, CRN, CAP) and Group2 (AFS, ASR, BSD, BSL, DSD, SPY, LPS). The north-south (N-S) latitudinal distribution shows that the SAP events are most prolific in the 21-30degree slice in the northern and southern hemispheres and east-west (E-W) longitudinal distribution study shows that the SAP events are most prolific (best visible) in the 81-90degree slice in the eastern and western hemispheres. It has been found that the SAP activity during this cycle is low compared to previous solar cycles. The present study indicates that during the rising phase of the cycle the number of SAP events were roughly equal on the north and south hemispheres. However, activity on the southern hemisphere has been dominant since 1999. Our statistical study shows that the N-S asymmetry is more significant then the E-W asymmetry.Comment: 21 pages 5 figures; Published online; 02 October, 2009; Solar Physics Journa
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