Heat and mass transfer in convective flow of an incompressible rarefied visco-elastic fluid in presence of transverse magnetic field

Analytical study is performed to examine heat and mass transfer characteristics of natural convection flow of an incompressible, rarefied visco-elastic fluid past an infinite vertical porous plate with constant suction in the presence of transverse magnetic field under combined buoyancy force effects of thermal and mass diffusion. The effects of various parameters on mean velocity and mean skin-friction are shown graphically followed by a comparative study of Newtonian and non-Newtonian (visco-elastic). rarefied states.     

X-ray spectral evolution of the extragalactic Z source LMC X-2

We present the results obtained by a detailed study of the extragalactic Z source LMC X-2, using broad-band Suzaku data and a large (∼750 ks) data set obtained with the proportional counter array (PCA) onboard the Rossi X-ray Timing Experiment ( RXTE ). The PCA data allow the study of the complete spectral evolution along the horizontal, normal and flaring branches of the Z track. Comparison with previous studies shows that the details of spectral evolution (like the variation of Comptonizing electron temperature) are similar to those of GX 17+2 but unlike those of Cyg X-2 and GX 349+2. This suggests that Z sources are a heterogeneous group, with perhaps LMC X-2 and GX 17+2 being members of a subclass. However, non-monotonic evolution of the Compton y parameter seems to be generic to all sources. The broad-band Suzaku data reveal that the case in which the additional soft component of the source is modelled as disc blackbody emission is strongly preferred over the one where it is taken to be a blackbody spectrum. This component, as well as the temperature of seed photons, does not vary when the source goes into flaring mode, and the entire variation can be ascribed to the Comptonizing cloud. The bolometric unabsorbed luminosity of the source is constrained to be  ∼2.23 × 10³⁸ erg s⁻¹  , which, if the source is Eddington-limited, implies a neutron star mass of  1.6 M_⊙  . We discuss the implications of these results.     

Study of the Diurnal Variation of Cosmic Rays during Different Phases of Solar Activity

The pressure-corrected hourly counting rate data of ground-based super neutron monitor stations, situated in different latitudes, have been employed to study the characteristics of the long-term variation of cosmic-ray diurnal anisotropy for a long (44-year) period (1965?–?2008). Some of these super neutron monitors are situated in low latitudes with high cutoff rigidity. Annual averages of the diurnal amplitudes and phases have been obtained for each station. It is found that the amplitude of the diurnal anisotropy varies with a period of one solar activity cycle (11 years), whereas the diurnal phase varies with a period of 22 years (one solar magnetic cycle). The average diurnal amplitudes and phases have also been calculated by grouping the days on the basis of ascending and descending periods of each solar cycle (Cycles 20, 21, 22, and 23). Systematic and significant differences are observed in the characteristics of the diurnal variation between the descending periods of the odd and even solar cycles. The overall vector averages of the descending periods of the even solar cycles (20 and 22) show significantly smaller diurnal amplitudes compared to the vector averages of the descending periods of the odd solar cycles (21 and 23). In contrast, we find a large diurnal phase shift to earlier hours only during the descending periods of even solar cycles (20 and 22), as compared to almost no shift in the diurnal phase during the descending periods of odd solar cycles. Further, the overall vector average diurnal amplitudes of the ascending period of odd and even solar cycles remain invariant from one ascending period to the other, or even between the even and odd solar cycles. However, we do find a significant diurnal phase shift to earlier hours during the ascending periods of odd solar cycles (21 and 23) in comparison to the diurnal phase in the ascending periods of even solar cycles (20 and 22).     

ALOS PALSAR and Hyperion Data Fusion for Land Use Land Cover Feature Extraction

Detailed and enhanced land use land cover (LULC) feature extraction is possible by merging the information extracted from two different sensors of different capability. In this study different pixel level image fusion algorithms (PCA, Brovey, Multiplicative, Wavelet and combination of PCA & IHS) are used for integrating the derived information like texture, roughness, polarization from microwave data and high spectral information from hyperspectral data. Span image which is total intensity image generated from Advanced Land observing Satellite-Phase array L-band SAR (ALOS-PALSAR) quad polarization data and EO-1 Hyperion data (242 spectral bands) were used for fusion. Overall PCA fused images had shown better result than other fusion techniques used in this study. However, Brovey fusion method was found good for differentiating urban features. Classification using support vector machines was conducted for classifying Hyperion, ALOS PALSAR and fused images. It was observed that overall classification accuracy and kappa coefficient with PCA fused images was relatively better than other fusion techniques as it was able to discriminate various LULC features more clearly.     

Ecosystem Services in a Transitional Forest Landscape: Shifting Trajectories in Southeast Michigan,USA

North American forests provide multiple ecosystem services, such as carbon storage, biodiversity, and recreation. These services are often coordinated through multifunctional management, whereby various users and owners contribute to collective agendas. Forests in exurban “transition” zones are crucial components in the sustainability of broader metropolitan landscapes, but represent a particularly understudied confluence of ecosystem services and multifunctional management. In this paper, we develop a place-based approach to assess ecosystem services in transitional forests (those between rural and urban). We demonstrate how trajectories of forest composition are linked with shifting ecosystem services that both shape and are shaped by management activities. Sited in Stinchfield Woods, a forest in southeast Michigan, this study draws on a household survey, interviews, ecological data, and archival information. Given variations in priorities over time and among different users, we suggest that coordinated, adaptive management may improve provisioning of ecosystem services in ways that benefit multiple users.     

Compensation of time‐delay for control of civil engineering structures

Time‐delay is an important issue in structural control. Applications of unsynchronized control forces due to time‐delay may result in a degradation of the control performance and it may even render the controlled structures to be unstable. In this paper, a state‐of‐the‐art review for available methods of time‐delay compensation is presented. Then, five methods for the compensation of fixed time‐delay are presented and investigated for active control of civil engineering structures. These include the recursive response method, state‐augmented compensation method, controllability based stabilization method, the Smith predictor method and the Pade approximation method, all are applicable to any control algorithm to be used for controlled design. Numerical simulations have been conducted for MDOF building models equipped with an active control system to demonstrate the stability and control performance of these time‐delay compensation methods. Finally, the stability and performance of the phase shift method, that is well‐known in civil engineering applications, have also been critically evaluated through numerical simulations. Copyright © 2000 John Wiley & Sons, Ltd.     

Stability assessment of slide zones in Lesser Himalayan part of Yamunotri pilgrimage route,Uttarakhand, India

The present study deals with the slope stability analysis and geotechnical assessment of a part of pilgrimage route to one of the holy shrines of India, i.e. Yamunotri. The route also embraces a proposed site for 204 m high concrete gravity dam across River Yamuna near Lakhwar village with the aim of generation of 300 MW power. Several slide zones were identified and based on the discontinuity orientation, structural features and debris materials, they are recognised as planar, wedge or circular failure types. The morphological dimensions, structural data, orientations and geotechnical parameters of circular failure slides within weathered quartzites, phyllites and shales were evaluated by extensive field work and by laboratory tests for their stability analysis. Internal mechanisms, cohesion and angle of internal friction that resist shear stress in slope materials, obtained from direct shear test are showing minor variation due to relatively consistent grain size distribution and mineralogical composition. General slope is about 40°–43° with sparse vegetation. Materials in and around slide zones are sands with appreciable amount of fines falling in SP–SM category as per Unified Soil Classification System (USCS), except Niste B slide which has clean sands lying in SP group. Factor of safety, computed by requisite parameters of strength, soil and slope properties in circular failure charts, varies from 1.02 to 1.23 in dry conditions while it reduces below unity with increasing saturation, representing stable conditions in dry conditions but with seepage and saturation along the cracks and discontinuities during rainfall make them unstable. Presence of steep slopes, proximity to stream channels and significant weathered and jointed area are causative factors in the route with rainfall and road widening as major triggers initiating the failure.     

Seasonal extreme rainfall variability over India and its association with surface air temperature

Theoretical and Applied Climatology - Spatial variability in catchment processes is crucial for hydrologic and water resources planning and management. The spatial density of ground-based rain...     

Spatial evaluation of groundwater quality in Kazhakuttam block,Thiruvananthapuram district,Kerala

The groundwater in the study area generally shows an acidic trend as evidenced by the low pH values, particularly in lateritic aquifers. Spatial assessment indicates that the southern part of the coastal aquifers shows elevated pollution levels during post monsoon season. Most of the groundwater is of Na-Cl facies in post monsoon and which slightly changes to Na-Mg-Cl facies during pre monsoon. Inter relationship between chemical parameters were also studied to understand the groundwater facies. Salinity hazard, percentage of sodium, SAR, integrated SAR and EC and RSC, were considered for judging the usefulness of groundwater for irrigation. Landuse map was prepared and water sample locations were superimposed on it, in a GIS platform, to assess the variation in water quality in different landuse classes. The outcome of the present study indicates that the concentration of certain parameters exceeds the recommended limits and hence mitigation measures are needed to be adopted to ensure safe drinking water.