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61.
On some shores the seawater is muddy, contaminated with fine silt and clay in suspension. If it became necessary to use such seawater it would be essential either to resort to filtration or to allow for settling of soil sediments. The present scheme was undertaken with a view to providing clear seawater for experimentation in growing crops and plants with seawater. The system consisted of a filtration unit embedded in the shore over which the tidal water passes. The clear water is run through a conveying assembly and is stored in a sump for end uses. The design, construction materials and construction operation of such a device on coastal sand dunes has been described in detail. The precautions to be taken under such circumstances are also given. 相似文献
62.
63.
GeoJournal - Application of geospatial technologies in criminological study is most relevant in present day context. Crime mapping with the help of Geographical Information System is being a very... 相似文献
64.
The application of piezo-ceramic elements for measuring shear and compression wave velocities in the soil mass is increasing
day-by-day. Depending upon the configuration and polarity, these elements can either be used as benders or extenders, which
can transmit and receive shear and compression waves, respectively. Though, several researchers have successfully employed
these elements for characterizing the soil mass based on the shear and compression wave velocities, determination of the “time
lag” between the input and output waves remains debatable. Even, the existing literature does not clearly present the response
of these elements with respect to the frequency of excitation and the type of the material to be characterized. With this
in view, extensive investigations were made to capture the performance of piezo-ceramic elements by changing their (a) wiring
configuration (i.e., series or parallel) and (b) polarization (i.e., same or opposite) in the compacted soils of different
characteristics (i.e., moisture content, dry density and type of the soil). Details of the methodology are presented in this
paper and special attention has been paid to address various problems (i.e., wave attenuation, crosstalk phenomena, near field
effect and overshooting of transmitting waves) that are associated with signal interpretation and may yield misleading results. 相似文献
65.
R. Nagendra Satish J. Patel Rakesh Deepankar A. N. Reddy 《Journal of the Geological Society of India》2010,76(5):525-532
Well preserved ichnofossils were found in Kulakkalnattam sandstone exposed at Kulakkalnattam stream in Ariyalur area, Cauvery Basin. It consists of infaunal structures of both suspension and deposit feeders. Five ichnofossils are present in a fine to coarse grain sandstone which includes Ophiomorpha, Palaeophycus, Planolites Skolithos, and Thalassinoides. The study infers that ichnofossils Skolithos and Ophiomorpha are infaunal colonization of the suspension feeders in high energy condition in shifting substrate, whereas Thalassinoides and Planolites-Palaeophycus ichnofossils indicate infaunal deposit feeders living at the sediment-sediment interface in low to moderate energy conditions. Furthermore, the abundance and diversity of the trace fossils indicates there was alternatively fluctuations in energy conditions which lead to development of Skolithos and Cruziana ichnofacies type condition during the deposition of Kulkkallanattam sandstone in foreshore-shoreface environments. 相似文献
66.
Titan’s north polar hydrocarbon lakes offer a unique opportunity to indirectly characterize the statistical properties of Titan’s landscape. The complexity of a shoreline can be related to the complexity of the landscape it is embedded in through fractal theory. We mapped the shorelines of 290 of the north polar titanian lakes in the Cassini synthetic aperture radar dataset. Out of these, we used a subset of 190 lake shorelines for our analysis. The fractal dimensions of the shorelines were calculated via two methods: the divider/ruler method and the box-counting method, at length scales of (1-10) km and found to average 1.27 and 1.32, respectively. The inferred power-spectral exponent of Titan’s topography (β) from theoretical and empirical relations is found to be ?2, which is lower than the values obtained from the global topography of the Earth or Venus. Some of the shorelines exhibit multi-fractal behavior (different fractal dimensions at different scales), which we interpret to signify a transition from one set of dominant surface processes to another. We did not observe any spatial variation in the fractal dimension with latitude; however we do report significant spatial variation of the fractal dimension with longitude. A systematic difference between the dimensions of orthogonal sections of lake shorelines is also noted, which signifies possible anisotropy in Titan’s topography. The topographic information thus gleaned can be used to constrain landscape evolution modeling to infer the dominant surface processes that sculpt the landscape of Titan. 相似文献
67.
In recent times, rapid urbanisation coupled with scarcity of land forces several structures to come up ever closer to each
other, which may sometime cause severe damage to the structures from both strength and serviceability point of view, and therefore,
a need is felt to devise simplified methods to capture the effect of footing interference. In the present study, an attempt
has been made to model the settlement behaviour of two strip footings placed in close spacing on layered soil deposit consisting
of a strong top layer underlying a weak bottom layer. Theory of elasticity is employed to derive the governing differential
equations and subsequently solved by the finite difference method. The perfectly rough strip footings are considered to be
resting on the surface of two-layer soil system, and the soil is assumed to behave as linear elastic material under a range
of static foundation load. The effect of various parameters such as the elastic moduli and thickness of two layers, clear
spacing between the footings and footing load on the settlement behaviour of closely spaced footings has been determined.
The variation of vertical normal stress at the interface of two different soil layers as well as at the base of the failure
domain also forms an important part of this study. The results are presented in terms of settlement ratio (ξδ), and their variation is obtained with the change in clear spacing between two footings. The present theoretical investigation
indicates that the settlement of closely spaced footings is found to be higher than that of single isolated footing, which
further reduces with increase in the spacing between the footings. 相似文献
68.
Stefanie Wachter Chryssa Kouveliotou Sandeep Patel Don Figer Peter Woods 《Astrophysics and Space Science》2007,308(1-4):67-71
Both Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) are thought to be manifestations of magnetars. However, the specific physical characteristics that differentiate the two classes of objects remain unclear. There is some evidence that the progenitors of these sources and/or the environment in which they form might influence the type of phenomena the resulting magnetar displays. Several of the AXPs appear to be associated with supernova remnants, while embedded clusters of massive stars have been found in the immediate vicinity of some SGRs. Since both AXPs and SGRs are distributed close to the Galactic plane, high extinction makes studies in the optical difficult. We present early results from our Spitzer program aimed at probing the environmental factors that might contribute to the difference in the observed characteristics between AXPs and SGRs. 相似文献
69.
N K Patel T T Medhavy C Patnaik A Hussain 《Journal of the Indian Society of Remote Sensing》1995,23(2):33-39
Microwave sensors having all-weather capabilities provide an opportunity to monitor rice grown in monsoon season. An attempt has been made to identify rice crop using multitemporal ERS-1 SAR data in C-band (5.3 GHz). Data acquired on August 15 (D1), September 19 (D2), October 24 (D3) and November 28 (D4) 1993 were taken. Combinations of data acquired on different dates were used for identification of rice crop. Single-date IRS-1B LISS II data in visible and NIR bands acquired on October 23, 1993 was also used for comparison of estimated rice area. Analysis of the results has shown that a combination of SAR data acquired at the tillering (August), booting (September) and heading (October) stages of rice crop enabled identification and area estimation of rice crop grown under lowland conditions. Single-date SAR data acquired in the month of October was found to be better for identification of rice compared to other dates. 相似文献
70.
Sushma Panigrahy S. S. Ray Anil Sood L. B. Patel P. K. Sharma J. S. Parihar 《Journal of the Indian Society of Remote Sensing》2004,32(2):209-216
A study was conducted in the Bathinda district of Punjab state for mapping the cropping pattern and crop rotation, monitoring
long term changes in cropping pattern by using the satellite based remote sensing data along other spatial and non-spatial
collateral data. Multi-date IRS LISS I and IRS WiFS sensor data have been used for this study. Cropping pattern maps and crop
rotation maps were generated for the years 1988-89 and 1998-99. The present study has shown the increase of cropping intensity
significantly, mainly due to increase in rice area. However, crop diversity has decreased mainly due to decline in the area
under the minor crops like pearl millet, gram, rapeseed/ mustard. There is increase in area coverage of cotton-wheat and rice-wheat
rotation, at the expense of the minor crops. 相似文献