An evaluation of national economic planning in the People's Republic of China     

Ashok K. Dutt  Frank J. Costa 《Geoforum》1980,11(1):1-15

The People's Republic of China has sought, since its inception in 1949, to develop through economic planning at the national level rather than rely on traditional free market mechanisms. This paper examines the changing characteristics of this economic planning over time, including the shifting balance between centralizing and decentralizing policies. The disruptive effects of the “Great Leap Forward” and the Cultural Revolution are also discussed and the general features of the contemporary situation are examined.  相似文献   

GIS assisted inverse geochemical modeling for plausible phase transfers in aquifers     

S. D. Dhiman  Ashok K. Keshari 《Environmental Geology》2006,50(8):1211-1219

A geographical information system (GIS) assisted approach that couples a groundwater flow model and an inverse geochemical model is presented to quantify the phase mole transfers between two points on the flow path within a groundwater system. It is used to investigate the plausible phase transfers in the unconfined aquifer of Mehsana district of Gujarat State, India. X-ray diffraction analysis of soil samples is carried out for mineral characterization. The groundwater flow field is simulated using MODFLOW and flow paths used for inverse geochemical modeling are traced using PMPATH, a particle tracking algorithm. The plausible phase mole transfers in the flow path are quantified using PHREEQC geochemical code. The different scenarios generated by inverse modeling routine are used as input to the geochemical model and simulation runs are taken as forward models. The obtained results are compared to the target solution chemistry by using the square of the Pearson product moment correlation coefficient. Results reveal that the groundwater is undersaturated with anhydrite, carbon dioxide (gas), fluorite, gypsum, halite, jarosite-K, and siderite. It is oversaturated with aragonite, calcite, dolomite, ferrihydrite, goethite, and hematite. Results further reveal that calcite is precipitating, while dolomite, gypsum, carbon dioxide, and fluorite are dissolving together with ion exchange in the flow path.  相似文献   

Extraction of geomorphological features using radarsat data     

Ashok Kaushal  Yogesh Singh 《Journal of the Indian Society of Remote Sensing》2006,34(3):299-307

A study was undertaken to evaluate the potential of RADARSAT SAR data (Standard-7 and Wide-2 beam positions) for delineating the geomophological units in Itanagar Capital Complex of Arunachal Pradesh, India. Principal Component Analysis (PCA) has been applied to Standard-7 and Wide-2 data with incidence angle 45° – 49° and 31 ° – 39° respectively. The resulting components yield imagery that highlights the Geomorphological units. The area of investigation has been classified into five geomophological units’ viz., High relief structural hills, low relief structural hills, low relief rugged hills, piedmont and intermontane valley. The surface roughness can be observed by studying the difference of the responses from different incidence angles. Wide-2 beam position was found to be more useful for identifying features in flat terrain, and Standard-7 beam position data for features of high relief.  相似文献   

Groundwater assessment through hydrogeomorphological and geophysical survey — A case study in Godavari sub-watershed, Giridih, Bihar     

Ashok Kumar  Savita Tomar 《Journal of the Indian Society of Remote Sensing》1998,26(4):177-183

Groundwater assessment has been carried out through hydrogeomorphological and geophysical survey. Remotely sensed data has been used to delineate the hydrogeomorphological units. Each hydrogeomorphological unit has been further sub-divided based on the tone, texture and pattern. These units its have been categorised based on depth of weathering, local geomorphological association, recharge characteristics etc. The top layer resistivity of hydrogeomorphological units has been analysed by electrical resistivity method. Correlation between different sub-units of same hydrogeomorphic unit and top soil resistivity has been attempted. The correlation and integration of resistivity map with geomorphological map were carried out through. ‘GRAM’ Geographic information System, This has helped in better understanding the surface resistivity pattern. These sub divisions have different geohydrological and recharge characteristics. Resistivity zonation map prepared on the basis of limited field data anfd through interpolation/extrapolation can be modified/corrected with the help of information derived from remotely sensed data to obtain more realistic picture.  相似文献   

Dynamics of Helically Twisted Prominence of January 22, 1979     

Nandita Srivastava  Ashok Ambastha 《Astrophysics and Space Science》1998,262(1):29-38

We have studied the dynamics of a macroscopically twisted helical prominence observed in H line on January 22, 1979 from Udaipur Solar Observatory. The analysis carried out is similar to that of March 11, 1979 event (Srivastava et al., 1991) wherein we had studied the role of twisted force-free magnetic fields in the prominence system. In the present study, it is found that of the two helically braided prominence tubes, one was dynamically more active. We have examined the temporal evolution of force-free parameter , and the axial currents associated with the prominence system that decreased with time. We find that the magnitude of the electric currents and also the rate of energy release during the untwisting of the prominence was of comparatively higher order 10³⁰ ergs s^-1 than that of March 11, 1979 event, in agreement with the physical dimensions of the two prominences.  相似文献   

Solar Photospheric and Chromospheric Observations using a Lithium Niobate Fabry-Perot Etalon     

C. Debi Prasad  Shibu K. Mathew  Arvind Bhatnagar  Ashok Ambastha 《Experimental Astronomy》1998,8(2):125-133

We have made a narrow band tunable filter for solar observations using a Lithium Niobate Fabry-Perot etalon. The 60 mm aperture etalon with a free spectral range of 4.22 Å and finesse of 26 at = 6122 Å has been procured from CSIRO, Australia. The wavelength tuning is achieved by applying high voltage to the etalon substrate at the rate of 0.45 Å per 1000 Volts. The filter is being used for imaging the sun in H line and obtaining Doppler- and Magnetogram in CaI 6122 Å line. In this paper, we present some initial observations carried out with this filter at Udaipur Solar Observatory.  相似文献   

Factorial ecology of Calcutta (1981) revisited     

Prof.  Dr. Ashok K. Dutt  Gerardine D'Sa  Prof.  Dr. Charles B. Monroe 《GeoJournal》1989,18(2):151-162

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Ranchi mega lineament and its correlation with geological and geophysical data     

Ashok Kumar  Deepak Srivastava  Sanjay Kumar Srivastava 《Journal of the Indian Society of Remote Sensing》1994,22(1):57-64

Remotely-sensed satellite data of Landsat 5 (TM) and IRS-1A (LISS II) covering parts of central portion of Chotanagapur plateau have been analysed visually to delineate some prominent lineaments in Ranchi district and its adjoining area. One of the most prominent lineament “Ranchi mega lineament? has been analysed in this paper. This lineament is a potential site for base metal mineralisation at some places, and it acts as good groundwater conduit in the region. No earlier attempt to map this entire structural unit as a separate entity is known. Geophysical bouguer gravity anomaly map, lithological and structural maps have some remarkable correlation with this lineament. In the present paper authors have tried to analyse the lineament with respect to its tectonic, mineralisation and groundwater prospects. Resistivity survey carried in close proximity of this lineament at selected sites, indicate that rocks are well fractured at depth. Available lithological and structural map support this lineament as a shear near Purulia (W.B.) and also having base-metal mineralisation potential in this area. Authors opine that existing gravity anomaly map may be further augmented in the light of present study.  相似文献   

Rank-size distribution and primate city characteristics in India — A temporal analysis     

Das RJ  Dutt AK 《GeoJournal》1993,29(2):125-137

This paper is an analysis of the historical change in city size distribution in India from the perspectives provided by Zipf and Jefferson. Rank-size distribution at national level and primate city-size distribution at regional levels are examined. India's national urban system is gradually evolving towards Zipf's rank-size distribution. But primate cities have persisted in three of the four macro-regions in India. The paper also examines, in the Indian context, the relation between rank-size distribution and an integrated urban system, and the normative nature of the latter as a spatial organization of human society. Finally, we have made a modest attempt to locate the research on city-size distribution, especially Berry's system-theoretic interpretation of rank-size distribution, on the realm of the political economy of urbanization.  相似文献   

Accretion-induced overstability of density waves in a self-gravitating disk     

Ashok Ambastha  R. K. Varma 《Astrophysics and Space Science》1978,55(2):459-473

A two-component differentially rotating disk of self-gravitating particles is considered in the hydrodynamical framework. This system is shown to sustain two pairs of density waves, corresponding to the familiar Jeans modes and an acoustic type of modes (similar to ion-acoustic modes in plasmas). As a result of mass and momentum transfer from the gaseous to the stellar component (an accretion process), the acoustic modes suffer a strong damping, whereas the Jeans modes which were oscillatory, now become overstable provided the thermal velocity of stars is larger than that of gaseous component. The waves with frequencies near the corotation have a rather large growth rate. This amplification can explain the maintenance of spiral structure and a selective amplification could even determine the wave-frequency (or pattern velocity).  相似文献