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41.
K. R. Rao R. Krishnan A. K. Chakraborthy B. L. Deekshatulu 《Journal of the Indian Society of Remote Sensing》1980,8(2):33-38
In the analysis of water quality by remote sensing, it is widely reported, that, several parameters of water quality are correlated with the reflectances and the ratios of reflectances of the water body in different spectral bands. In this paper, it is shown empirically, that, the pairwise product of the reflectances in different bands is better correlated than the bands and their ratios. A possible explanation for this pnenomenon is also suggested. 相似文献
42.
K. S. Rao Girish Chandra C. Suresh Raju 《Journal of the Indian Society of Remote Sensing》1987,15(2):53-63
The dielectric property of the soil is an important parameter for microwave remote sensing. Therefore an attempt is made to study and compare the models for the dielectric constant of moist soils by considering three soil types namely Haldi series (sandy loam), Hathiapathar series (silt loam) and Jambria series (clay) and at frequencies 1.4, 4.0 and 18.0 GHz. The semiempirical models of Wang et al. (1980) and Dobson et al (1985) predict more or les same results in the domain of their applicability. However, at lower frequencies below 1.0 GHz, the imaginary part of dielectric constant shows a decreasing trend with decreasing frequency for Wang et al (1980) model whereas it shows reverse trend for Dobson et al (1985) model. The soil texture and frequency dependence of dielectric constant have been investigated for Indian soils. Some of the representative dielectric profiles of black soils of Pune have been computed using semiempirical model of Dobson et al (1985) which are useful for the development of multifrequency models for the study of soil moisture. 相似文献
43.
P. Prabhakara Rao K. C. C. Raju M. Kareemuddin 《Journal of the Indian Society of Remote Sensing》1982,10(2):45-53
Multi-disciplinary integrated studies were carried out in the drought prone, backward district of Anantapur, for an appraisal of its natural resource and environmental potential, by applying the photointerpretation and remote sensing techniques. Shortage of land and water resources are identified as the major constraints for developmental planning. The natural resources and the potential available for development are documented in various thematic maps. The landuse pattern for agriculture and forestry is mainly controlled by the lithological and morphological units. It is surmised, that with the new source for groend water identified along linement and fracture zones, there is scope for augmenting and uplift the land use and crop-pattern, and this helps to upgrade the socio-economic condition of the district. 相似文献
44.
P. P. Nageswara Rao A. S. Padmavathy 《Journal of the Indian Society of Remote Sensing》1985,13(2):13-18
In the present study the effect of solar elevation angle on the spectral response of rice crop was examined under farmer’s field conditions. The aim of the study is to see if band ratioing can reduce the effect of soiar elevation angle on rice crop spectral response. It was observed that the spectral transformations involving red and near infrared are highly useful in normalizing the effect of sun elevation when the canopy cover is complete. Contrary to this, the spectral transformation could not normalize the effect of sun elevation on the spectral response of rice crop when the canopy cover is incomplete. 相似文献
45.
With the advent of new global navigation satellite systems (GNSSs) and new signals, GNSS users will rely more on them to obtain higher-accuracy positioning. Evil waveform monitoring and assessment are of great importance for GNSS to achieve its positioning, velocity, and timing service with high accuracy. However, the advent of new navigation signals introduces the necessity to extend the traditional analyzing techniques already accepted for binary phase-shift keying modulation to new techniques. First, the well-known second-order step thread model adopted by the International Civil Aviation Organization is introduced. Then the extended new general thread models are developed for the new binary offset carrier modulated signals. However, no research has been done on navigation signal waveform symmetry yet. Simulation results showed that, waveform asymmetry may also cause tracking errors, range biases, and position errors in GNSS receivers. It is thus imperative that the asymmetry be quantified to enable the design of appropriate error budgets and mitigation strategies for various application fields. A novel evil waveform analysis method, called waveform rising and falling edge symmetry (WRaFES) method, is proposed. Based on this WRaFES method, the correlation metrics are provided to detect asymmetric correlation peaks distorted by received signal asymmetry. Then the statistical properties of the proposed methods are analyzed, and a proper deformation detection threshold is calculated. Finally, both simulation results and experimentally measured results of Beidou navigation satellite system (BDS) M1-S B1Cd signal are given, which show the effectiveness and robustness of the proposed thread models. 相似文献
46.
Raja Sengupta Griet Vankeerberghen Ruoxuan Wen Jing Rao Yanbing Chen 《Transactions in GIS》2023,27(4):1090-1103
GIS-enabled historiography allows us to shed light on missing or poorly understood aspects of historical events. Here, we use agent-based models (ABMs), least cost path analysis (LCPA), and space–time paths to recreate and evaluate possible modes and routes of travel undertaken by Shi Rao, a Western Han official. A diary was found in Shi Rao's tomb that includes information about his travels over 1 year (11 BCE), including start and end times of his journeys. But it leaves out details regarding modes of transport or exact routes. Using Tan Qixiang's historical atlas, we digitized river networks and utilized modern topographic data to digitally recreate the landscape as it was during Shi Rao's travels. This was then used to evaluate possible journeys via rivers (using ABMs) and roads (using LCPA), and compared to historical speed of boats, carts and horses, with findings indicating that horseback may have been the viable option. 相似文献
47.
P. C. Padhy R. K. Nayak V. K. Dadhwal M. Salim D. Mitra S. B. Chaudhury P. R. Rao K. H. Rao C.B. S. Dutt 《Journal of the Indian Society of Remote Sensing》2016,44(1):135-143
An empirical model is developed and used with remotely sensed predictors: sea surface temperature (SST) and chlorophyll-a concentration (Chl-a), to compute surface water partial pressure of carbon dioxide (pCO2w) and air-sea fluxes of CO2 in the Hooghly estuary and its adjacent coastal oceans. In situ observations used here were based on measurements carried out in this region during winter and summer periods in 2008. The estimated pCO2w compares well with the in situ observations at root mean square error ±18 μatm. In winter, estimated pCO2w ranges between 320 and 500 μatm with large values (>400 μatm) on the south-western and south-eastern flanks of the coastal domain and lower values (340–375 μatm) on the main-channel. In summer, it remained spatially uniform at 450 μatm. Extrapolation of the results over the study region based on the Moderate Imaging Specroradiometer (MODIS) measured SST and Chl-a suggests that the region is a strong source of atmospheric CO2 during the summer with net release of 0.095 Tg C year?1 (equivalent to mean flux of 90 molC m?2 year?1) and is a weak source during the winter with net release of 0.006 Tg C yr?1 (0.5 molC m?2 year?1) from the geographical extent of 6000 Km2 area. 相似文献
48.
付娆 《测绘与空间地理信息》2013,(10):151-153
简明地描述了MapGIS对线性地物的拓扑处理使用情况和一些使用方法的实现,同时介绍MapGIS拓扑处理部分功能的应用和技巧。 相似文献
49.
Pratima M. Kessarkar V. Purnachandra Rao R. Shynu Ishfaq Mir Ahmad Prakash Mehra G. S. Michael D. Sundar 《Journal of Earth System Science》2009,118(4):369-377
Systematic studies on the suspended particulate matter (SPM) measured on a seasonal cycle in the Mandovi Estuary, Goa indicate
that the average concentrations of SPM at the regular station are ∼20mg/l, 5mg/l, 19mg/l and 5mg/l for June–September, October–January,
February–April and May, respectively. SPM exhibits low-to-moderate correlation with rainfall indicating that SPM is also influenced
by other processes. Transect stations reveal that the SPM at sea-end stations of the estuary are at least two orders of magnitude
greater than those at the river-end during the monsoon. Estuarine turbidity maximum (ETM) of nearly similar magnitude occurs
at the same location in two periods, interrupted by a period with very low SPM concentrations. The ETM occurring in June–September
is associated with low salinities; its formation is attributed to the interactions between strong southwesterly winds (5.1–5.6ms−1) and wind-induced waves and tidal currents and, dominant easterly river flow at the mouth of the estuary. The ETM occurring
in February–April is associated with high salinity and is conspicuous. The strong NW and SW winds (3.2–3.7ms−1) and wind-driven waves and currents seem to have acted effectively at the mouth of the estuary in developing turbidity maximum.
The impact of sea breeze appears nearly same as that of trade winds and cannot be underestimated in sediment resuspension
and deposition 相似文献
50.
Magnetic anomalies of offshore Krishna-Godavari basin,eastern continental margin of India 总被引:1,自引:0,他引:1
K. V. Swamy I. V. Radhakrishna Murthy K. S. Krishna K. S. R. Murthy A. S. Subrahmanyam M. M. Malleswara Rao 《Journal of Earth System Science》2009,118(4):405-412
The marine magnetic data acquired from offshore Krishna-Godavari (K-G) basin, eastern continental margin of India (ECMI),
brought out a prominent NE-SW trending feature, which could be explained by a buried structural high formed by volcanic activity.
The magnetic anomaly feature is also associated with a distinct negative gravity anomaly similar to the one associated with
85°E Ridge. The gravity low could be attributed to a flexure at the Moho boundary, which could in turn be filled with the
volcanic material. Inversion of the magnetic and gravity anomalies was also carried out to establish the similarity of anomalies
of the two geological features (structural high on the margin and the 85°E Ridge) and their interpretations. In both cases,
the magnetic anomalies were caused dominantly by the magnetization contrast between the volcanic material and the surrounding
oceanic crust, whereas the low gravity anomalies are by the flexures of the order of 3–4 km at Moho boundary beneath them.
The analysis suggests that both structural high present in offshore Krishna-Godavari basin and the 85°E Ridge have been emplaced
on relatively older oceanic crust by a common volcanic process, but at discrete times, and that several of the gravity lows
in the Bay of Bengal can be attributed to flexures on the Moho, each created due to the load of volcanic material. 相似文献