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匹配条件: “P. K. Das” ,找到相关结果约316320条。
Heavy Mineral Potentiality and Alteration Studies for Ilmenite in Astaranga Beach Sands, District Puri, Odisha, India  [PDF]
Sanuprava Mohapatra, P. Behera, S. K. Das
Journal of Geoscience and Environment Protection (GEP) , 2015, DOI: 10.4236/gep.2015.31005
Abstract: Fifteen beach sand samples were collected from a depth of 1mt at different locations of the Astaranga beach, Puri with an interval of 300 mts. The beach sand samples were studied for heavy mineral concentration at different location points and were subjected to scanning electron microscope studies for the mineral ilmenite. The percentage of total heavy mineral in Astaranga beach varies from 16.42% to 24.47%. The important minerals are ilmenite, rutile, zircon, sillimanite, garnet, monazite, pyroxene and others. For all samples a set of sieves bearing ASTM nos. 30, 40, 60, 80, 100, 120, 140, 170 and 200 corresponding to 0.59 mm, 0.42 mm, 0.25 mm, 0.177 mm, 0.149 mm, 0.125 mm, 0.105 mm, 0.088 mm and 0.074 mm respectively were used to separate different size fractions. The sieve mesh sizes vary from 0.59 mm to 0.74 mm. It was observed that maximum concentration of heavies was confined to +200 ASTM sieve or 0.74 mm. The total average heavy mineral concentration and light mineral concentration was found to be 20.07% and 79.49% respectively. The concentration percentage of different heavy minerals varied from higher to lower in the order like ilmenite, zircon, sillimanite, garnet, rutile, pyroxene, monazite and others. The ilmenite mineral in this area is found to have altered to secondary phases like pseudorutile, leucoxene and rutile along the fractures, cavities and grain boundaries. The alteration condition was observed as streaks, irregular patches, bands, and rim like structures around the ilmenite grains. Detailed study of alteration in ilmenite was carried out by Energy Dispersive Spectrometer (EDS) attached to Scanning Electron Microscope. The potentialities of heavies found at different locations of the Astaranga beach suggested a good source for the exploration. The alteration of the mineral ilmenite and high concentration of heavy minerals clearly pointed to the sedimentary environment and mechanical concentration process due to repeated wave action.
Effective Beneficiation of Low Grade Iron Ore Through Jigging Operation  [PDF]
B. Das, S. Prakash, S.K. Das, P.S.R. Reddy
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2008, DOI: 10.4236/jmmce.2008.71002
Abstract: The effectiveness of jigging operation for the beneficiation of low-grade iron ore deposits of Orissa, India has been investigated. Iron ore sample obtained from Barbil region of Orissa containing very high amount of silica and alumina was crushed using the laboratory jaw crusher and roll crusher to prepare different particle sizes. The sink and float tests were carried out to evaluate the possible response of the sample by gravity concentration technique. The samples were subjected to jigging in a laboratory Denver mineral jig and Harz jig. The operating variables used to determine the effectiveness of jigging include, particle size, velocity of water and amplitude. Recovery of iron values and the separation efficiency were assessed by determining mineralogy and the percentages of Fe in the jig concentrate and tailings by wet chemical and X-ray floroscence (XRF) techniques. Optimum iron ore recovery of 78.6% was achieved with 63.7% Fe in concentrate when the jig was operated at medium stroke, with an average water velocity and at a particle size of below 5 mm. The results are very close to theoretical results obtained by sink and float studies.
Dust ion acoustic solitary structures in nonthermal dusty plasma
Animesh Das,Anup Bandyopadhyay,K P Das
Physics , 2011, DOI: 10.1017/S002237781100050X
Abstract: Dust ion acoustic solitary structures have been investigated in an unmagnetized nonthermal plasma consisting of negatively charged dust grains, adiabatic positive ions and nonthermal electrons. For isothermal electrons, the present plasma system does not support any double layer solution, whereas for nonthermal electrons, negative potential double layer starts to occur whenever the nonthermal parameter exceeds a critical value. However this double layer solution is unable to restrict the occurrence of all negative potential solitary waves of the present system. As a result, two different types of negative potential solitary waves have been observed, in which occurrence of first type of solitary wave is restricted by M_cM_D, where M_c is the lower bound of Mach number M and M_D(>M_c) is the Mach number corresponding to a negative potential double layer. A finite jump between the amplitudes of negative potential of solitary waves at M=M_D-\epsilon_1 and at M=M_D+\epsilon_2 has been observed, where 0<\epsilon_10. An analytical theory for the existence of double layer has been presented. A numerical scheme has also been provided to find the value of Mach number at which double layer solution exists and also the amplitude of that double layer. Although the occurrence of coexistence of solitary structures of both polarities is restricted by M_cM_max, where M_max is the upper bound of M for the existence of positive potential solitary waves only. Qualitatively different compositional parameter spaces showing the nature of existing solitary structures of the energy integral have been found. These solution spaces are capable of producing new results and physical ideas for the formation of solitary structures.
Existence of dust ion acoustic solitary wave and double layer solution at M = Mc
Animesh Das,Anup Bandyopadhyay,K. P. Das
Physics , 2011,
Abstract: The Sagdeev potential technique has been used to investigate the existence and the polarity of dust ion acoustic solitary structures in an unmagnetized collisionless nonthermal dusty plasma consisting of negatively charged static dust grains, adiabatic warm ions and nonthermal electrons when the velocity of the wave frame is equal to the linearized velocity of the dust ion acoustic wave for long wave length plane wave perturbation, i.e., when the velocity of the solitary structure is equal to the acoustic speed. A compositional parameter space has been drawn which shows the nature of existence and the polarity of dust ion acoustic solitary structures at the acoustic speed. This compositional parameter space clearly indicates the regions for the existence of positive and negative potential dust ion acoustic solitary structures. Again, this compositional parameter space shows that the present system supports the negative potential double layer at the acoustic speed along a particular curve in the parametric plane. However, the negative potential double layer is unable to restrict the occurrence of all negative potential solitary waves. As a result, in a particular region of the parameter space, there exist negative potential solitary waves after the formation of negative potential double layer. But the amplitudes of these supersolitons are bounded. A finite jump between amplitudes of negative potential solitons separated by the negative potential double layer has been observed, and consequently, the present system supports the supersolitons at the acoustic speed in a neighbourhood of the curve along which negative potential double layer exist. The effects of the parameters on the amplitude of the solitary structures at the acoustic speed have been discussed.
Effect of Landau damping on alternative ion-acoustic solitary waves in a magnetized plasma consisting of warm adiabatic ions and non-thermal electrons
Jayasree Das,Anup Bandyopadhyay,K. P. Das
Physics , 2015,
Abstract: Bandyopadhyay and Das [Phys. Plasmas, 9, 465-473, 2002] have derived a nonlinear macroscopic evolution equation for ion acoustic wave in a magnetized plasma consisting of warm adiabatic ions and non-thermal electrons including the effect of Landau damping. In that paper they have also derived the corresponding nonlinear evolution equation when coefficient of the nonlinear term of the above mentioned macroscopic evolution equation vanishes, the nonlinear behaviour of the ion acoustic wave is described by a modified macroscopic evolution equation. But they have not considered the case when the coefficient is very near to zero. This is the case we consider in this paper and we derive the corresponding evolution equation including the effect of Landau damping. Finally, a solitary wave solution of this macroscopic evolution is obtained, whose amplitude is found to decay slowly with time.
Reversible and (n_1,n_2)-blockwise reversible code
P. K. Das,V. Tyagi
International Journal of Algebra , 2012,
Codes Detecting and Locating Periodic Errors
P. K. Das,Vinod Tyagi
Journal of Theoretical Physics and Cryptography , 2013,
Abstract: Error-locating codes (EL codes), first proposed by J. K. Wolf and B. Elspas in 1963, have the potential to be used to identify the faulty module for fault isolation and reconfiguration in fault-tolerant computer systems. This paper proposes a new class of EL codes suitable for systems with periodic errors. The authors obtain lower and upper bounds on the number of parity check digits required for a linear code that detects and locates errors which are periodic in nature. An illustration of such a code is also provided.
Frequency Adapted Phase Transition of Interacting Nano-Magnetic Ensemble
Nilangshu K. Das,P. Barat
Physics , 2013,
Abstract: Each single domain nano-magnet acts as a magnetic dipole in addition it oscillates its magnetization about the easy axis and rotates coherently depending upon temperature and anisotropy. In an ensemble of nano-magnets, the relaxation time of a nano-magnet tunes with the long range dipolar interaction which in turn is determined by the particle size, density and the number of nano-magnets present in the ensemble. Hence, the aggregation of interacting nano-magnetic dipoles, demonstrates both experimentally and theoretically as a model system to detect intriguing co-operative physical phenomena. Here we show a new variant of phase transition from paramagnetic to diamagnetic phase by changing the frequency of the applied sinusoidal magnetic field for a nano-magnetic ensemble. This phenomenon unravels a new insight of physics and it may be significant on the design and development of magnetic devices. The simulation of the system is well in agreement with the experimental results.
A (T-P) phase diagram of hydrogen storage on (N4C3H)6Li6 and the possibility of an associated new functional material
R. Das,P. K. Chattaraj
Physics , 2011,
Abstract: A temperature-pressure phase diagram has been generated through the study of hydrogen adsorption on the (N_4 C_3 H)_6Li_6 cluster at the B3LYP/6-31G(d) level of theory. Possibility of hydrogen storage in an associated 3D functional material has been also explored.
On fuzzy weakly-closed sets
J. Mahanta,P. K. Das
Mathematics , 2012, DOI: 10.5120/6076-8187
Abstract: A new class of fuzzy closed sets, namely fuzzy weakly closed set in a fuzzy topological space is introduced and it is established that this class of fuzzy closed sets lies between fuzzy closed sets and fuzzy generalized closed sets. Alongwith the study of fundamental results of such closed sets, we define and characterize fuzzy weakly compact space and fuzzy weakly closed space.

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