Relationship Between the Momentum and Scalar Fluxes Close to the Ground During the Indian Post-monsoon Period     

Subharthi Chowdhuri  Thara V. Prabha  Anand Karipot  T. Dharamraj  M. N. Patil 《Boundary-Layer Meteorology》2015,154(2):333-348

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Diurnal variations of the low-level jet over peninsular India during the onset of Asian summer monsoon     

Sandhya K. Nair  Thara V. Prabha  N. Purushothaman  S. Sijikumar  S. Muralidharan  N. V. P. Kirankumar  D. B. Subrahamanyam  T. J. Anurose  S. S. Prijith  K. V. S. Namboodiri 《Theoretical and Applied Climatology》2015,120(1-2):287-298

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Experimental Investigations on Laminated Rubber Bearings   总被引：1，自引：0，他引：1  

Sarvesh?Kumar?JainEmail author  Shashi?Kant?Thakkar 《Bulletin of Earthquake Engineering》2005,3(1):129-136

Increasing application of base isolation as a seismic protection method has subsequently increased its analytical and experimental studies. Being the most critical part of the base isolated buildings, accurate evaluation of structural properties and precise modeling of isolation devices is of utmost importance in predicting the response of the buildings during the earthquakes. This technical note is concerned with experimental study on laminated rubber bearings. Free vibration and harmonic base excitation tests are performed on a three-storey building model to evaluate the properties of the structure, efficiency of the system, and effect of base excitations. It is found that these experimental methods can effectively be used for this purpose.  相似文献   

Short-term changes in the aerosol characteristics at Kharagpur (22°19′N, 87°19′E) during winter     

Prabha R. Nair  K. Susan George  K. Parameswaran  Marina Aloysius  Denny P. Alappattu  Mannil Mohan  P.K. Kunhikrishnan 《Journal of Atmospheric and Solar》2009,71(17-18):1771-1783

In-situ measurements of number density, size distribution, and mass loading of near-surface aerosols were carried out at Kharagpur, a site on the eastern part of Indo-Gangetic Plains during the winter month of December 2004. The data have been used to investigate wintertime characteristics of aerosols and their effects on the occurrence of haze. The aerosol number density is found to be of the order of 10⁹ m^?3 and mass loading is ~265±70 μg m^?3 (5–8 times that reported from south Indian sites). The diurnal patterns and day-to-day variations in aerosol number density and mass loading are closely associated with atmospheric boundary layer height. During haze events, the number density of submicron particles is found to be 2–5 times higher than that during non-hazy period. This could be attributed to the enhanced concentration of anthropogenic aerosols, low atmospheric boundary layer height/ventilation coefficient and airflow convergence.  相似文献   

Simulation of meteorological fields over a land-water-land terrain and comparison with observations     

Thara V. Prabha  R. Venkatesan  V. Sitaraman 《Boundary-Layer Meteorology》1999,91(2):227-257

A numerical two-dimensional-mesoscale model with a level 1.5 closure scheme for turbulence is described. The model is used to simulate the boundary layer over coastal complex terrain. Meteorological data available from the Øresund land-sea-land terrain experiment are used to study the performance of the model. The model could simulate generally observed complexities in the mean wind and temperature fields. Internal boundary layers over the water and land surfaces were identified by the height of lowest value in the turbulence kinetic energy profile and this showed good agreement with radiosonde (RS) observations.Some disagreements with the data were also noticed, especially near the surface. The wind speed was over-predicted. Attempts were made to improve the model performance by adopting different schemes for model initialisation. Results showed that initialisation with an early model start time and observed wind profile near the inflow boundary improved the performance. The wind speed over-prediction could be further minimised by using a more realistic objective initialisation scheme. The problem centred around the proper estimation of the turbulent diffusion coefficient K through the closure scheme. Despite using the most popular empirical relationships in the level 1.5 closure scheme, these differences persisted. While this needs further investigation, the present model can be used to supply wind fields for practical purposes such as air pollution calculations.  相似文献   

Modeling of Diffusion in a Wide Alpine Valley     

T. V. Prabha  E. Mursch-Radlgruber 《Theoretical and Applied Climatology》1999,64(1-2):93-103

Summary  A K-type diffusion model coupled with a massconsistent wind model is applied for one of the rural biological waste disposal sites in Austrian Alps. The site is situated in the P?ls valley in the eastern Alps, 250 km south-west of Vienna in Austria Aim of the study is to demonstrate dispersion of H₂S from the site to near by village. Model simulations are carried out each for an evening and a morning transition case characterized by flow reversals. The role of locally generated wind in changing the pollutant distribution over nearby residential area is investigated. Surface observations at two stations toward the open boundaries of the main valley are used to derive the turbulence parameters and then to obtain initial inputs of wind profiles. The turbulence parameters behave analogous to that over a plane terrain after the establishment of the valley wind. The model simulations are done for eight hours during the evening transition and eighteen hours for the morning transition by incorporating the wind field from a mass consistent wind model. The results are compared with SF₆ tracer experiments conducted during those periods. The model outputs and the observations at various points inside the valley are in good correlation except for NW part of the valley after the reversal of valley wind. The results also reveal the potential of a simple approach with minimized inputs. Received August 15, 1997 Revised August 15, 1998  相似文献   

Ecological variables influencing the diversity and distribution of macrolichens colonizing <Emphasis Type="Italic">Quercus leucotrichophora</Emphasis> in Uttarakhand forest     

Shashi Upadhyay  Arun K. Jugran  Yogesh Joshi  Renu Suyal  Ranbeer S. Rawal 《山地科学学报》2018,15(2):307-318

Ecological variables play a significant role in determining the diversity and distribution of any living organism on earth. Lichens are not exceptional and are quite sensitive in comparison to other organisms; hence the present study focuses on the impact of ecological variables on the diversity and distribution of epiphytic macrolichens colonizing Quercus leucotrichophora across eight different sites (50 m × 50 m) in Thal Ke Dhar forest, Kumaun Himalaya, Uttarakhand, India. For sampling of macrolichens, 200 trees (25 trees from each site) of Q. leucotrichophora were selected from each site and five quadrats of 5 cm × 10 cm (1000 quadrats in totality) were drawn at the tree trunk. From all the sampled trees, a total of 54 species of epiphytic macrolichens belonging to 18 genera and five families were recorded. Various ecological variables, namely altitude, aspect, slope, diameter at breast height (DBH), and lopping percent (partial cutting of the twigs as disturbance), were also analyzed to investigate their influence on macrolichen species composition and distribution pattern in the study area. For the determination of relationships between these variables, statistical analysis, namely Pearson’s Correlation Coefficient, Polynomial regression analysis and Principal Component Analysis (PCA) were performed. Out of all variables, lopping was significantly correlated to species richness of epiphytic macrolichens (0.712*, p<0.05) and it was confirmed by Pearson’s Correlation Coefficient. Despite of having high anthropogenic pressure or impact through lopping, the maximum number of macrolichen species was recorded at elevation 2267 meter above sea level (m asl). The present study revealed that besides other ecological variables, lopping practices can act as a key parameter in controlling the diversity and distribution not only of epiphytic macrolichens but also of other life forms such as bryophytes, pteridophytes, insects, birds etc. and can be either negatively or positively correlated.  相似文献   

The value of recreational fishing in the Great Barrier Reef, Australia: A pooled revealed preference and contingent behaviour model   总被引：2，自引：0，他引：2  

Prabha Prayaga  John Rolfe  Natalie Stoeckl   《Marine Policy》2010,34(2):244-251

Given the focus on protecting natural assets in the Great Barrier Reef Marine Park in Australia, it is important for managers and policy makers to understand the value of recreational fishing in the area, and how changes in management may affect those recreational values. Travel cost methods were used to estimate the value of recreational fishing in the Capricorn Coast in Central Queensland using data from on-site surveys conducted at boat ramps. The study also uses contingent behaviour models to estimate the change in the value of recreational fishing as conditions vary. Results indicate that there are high values associated with recreational fishing activity along the Capricorn Coast, and that the demand for recreational fishing is inelastic and that values are relatively insensitive to changes in catch rates.  相似文献   

Adsorption of Cadmium from Aqueous Solution by Ficus religiosa Leaf Powder and Characterization of Loaded Biosorbent     

Karanam Srinivasa Rao  Shashi Anand  Paladugu Venkateswarlu 《洁净——土壤、空气、水》2011,39(4):384-391

The present investigation evaluates the adsorption effectiveness of Cd(II) ions on Ficus religiosa leaf powder (FRL). The experimental parameters chosen included time, pH, particle size, temperature, adsorbate, anion, and Pb(II) concentrations. The time data followed pseudo‐second‐order kinetics. Cd(II) adsorption increased from 1.38 to 75.17% with the increase in pH from 2 to 4 and further increase in pH to 5.5 resulted in its marginal increase to 77.52%. Based on regression coefficient values, the isothermic data fitted the various models in the order Langmuir > Redlich–Peterson > Temkin > Freundlich model. The maximum loading capacity of FRL was estimated to be 27.14 mg g^?1. The presence of Cl^?, , or Pb²⁺ exhibited adverse effect on Cd(II) uptake. The thermodynamic parameters of enthalpy (ΔH⁰) and entropy (ΔS⁰) were estimated to be 8.31 kJ mol^?1 and 38.22 J mol^?1 K^?1, respectively. SEM‐EPMA of the loaded FRL showed Cd(II) distribution at specific sites. The XRD patterns of Cd(II) loaded FRL sample showed disappearance of some peaks corresponding to β‐Ca(PO₃)₂; shifting of peaks and decrease in %RI corresponding to γ‐CaSO₄ phase. Positive shift of IR bands for the Cd(II) loaded sample was observed.  相似文献   

Resolution of multiple sheet-type structures in self-potential measurement     

Arkoprovo Biswas  Shashi Prakash Sharma 《Journal of Earth System Science》2014,123(4):809-825

The resolution of self-potential anomalies due to closely spaced multiple sheet-like bodies by the potential difference and potential gradient is studied in this paper. Self-potential anomalies due to several synthetic models were inverted through a very fast simulated annealing (VFSA) global optimization. Increase in depth to the top, polarization constant and depth extent of the body decreases resolution at a particular target separation. It has been observed that depth to the top and separation between two targets play an important role in the resolution. Vertical sheets at equal depth can be resolved in the potential difference measurement only if they are separated by at least four times their depth, while they can be resolved in the gradient method, if they are separated by twice the depth. Resolution using potential difference becomes more difficult for dipping sheets, although the potential gradient method can resolve them efficiently. Efficacy of potential gradient data in the inversion is demonstrated in the study using synthetic data as well as field measurement from South Purulia Shear Zone related with uranium investigation.  相似文献