High resolution shallow seismic data was acquired from inner continental shelf of Goa,west coast of India to map underlying stratigraphic and buried geomorphic features of shelf strata.Seismic data revealed characteri...High resolution shallow seismic data was acquired from inner continental shelf of Goa,west coast of India to map underlying stratigraphic and buried geomorphic features of shelf strata.Seismic data revealed characteristic channel incisions beneath 4-15 m thick sediment layer and corresponds to multi cycle incisions.Stratigraphic analysis of these incision signatures reveals three prominent subaerial unconformities S6,S7 and S9.These unconformities were exposed during the last glacial,penultimate glacial(MIS-6)and prior to penultimate glacial(MIS-8)periods.On the basis of interpreted age of subaerial unconformities and differences in their morphological features,observed channel incisions have been divided grossly into three phases of incision.Phase-1 incisions are older than^330 kyr BP,whereas,incisions of Phase-2 and Phase-3 correspond to^320-125 kyr BP and^115-10 kyr BP respectively.Plan form of these incisions varied from a straight channel type to ingrown meander and then to anastomosing channel types.These channels meet at the confluence of present-day Mandovi and Zuari rivers.The confluence point has varied in due course of time because of cyclic incision and burial with repeated sea level fluctuations.The preserved main channel width varies from^100 m to 1000 m.and maximum channel depth reaches up to^35 m.Comparison of quantitative and qualitative morphologic results of different phases of incisions suggest that Phase-2 channels had^33%more mean bank full discharge than that of the Phase-3 channels.Phase-2 incisions had been carved in higher hydraulic energy condition as compared to Phase-3 incisions implying that the Indian summer monsoon was better during formative stages of Phase-2 incisions.展开更多
Mg-7.6% Al （in mass fraction） alloy matrix composites reinforced with different volume fractions of nano- crystalline Al3Cas particles were synthesized by powder metallurgy, and the effect of the volume fraction of ...Mg-7.6% Al （in mass fraction） alloy matrix composites reinforced with different volume fractions of nano- crystalline Al3Cas particles were synthesized by powder metallurgy, and the effect of the volume fraction of reinforcement on the mechanical properties was studied. Room temperature compression test reveals considerable improvement on mechanical properties as compared to unreinforced matrix. The compressive strength increases from 683 MPa for unre- inforced alloy matrix to about 767 and 823 MPa for the samples having 20 and 40 vol% of reinforcement, respectively, while retaining appreciable plastic deformation ranging between 12 and 24%. The specific strength of the composites increased significantly, demonstrating the effectiveness of the low-density AlaCas reinforcement.展开更多
基金financial support as JRF&SRF(Fellowship letter No.23/12/2012(ii)EU-V)
文摘High resolution shallow seismic data was acquired from inner continental shelf of Goa,west coast of India to map underlying stratigraphic and buried geomorphic features of shelf strata.Seismic data revealed characteristic channel incisions beneath 4-15 m thick sediment layer and corresponds to multi cycle incisions.Stratigraphic analysis of these incision signatures reveals three prominent subaerial unconformities S6,S7 and S9.These unconformities were exposed during the last glacial,penultimate glacial(MIS-6)and prior to penultimate glacial(MIS-8)periods.On the basis of interpreted age of subaerial unconformities and differences in their morphological features,observed channel incisions have been divided grossly into three phases of incision.Phase-1 incisions are older than^330 kyr BP,whereas,incisions of Phase-2 and Phase-3 correspond to^320-125 kyr BP and^115-10 kyr BP respectively.Plan form of these incisions varied from a straight channel type to ingrown meander and then to anastomosing channel types.These channels meet at the confluence of present-day Mandovi and Zuari rivers.The confluence point has varied in due course of time because of cyclic incision and burial with repeated sea level fluctuations.The preserved main channel width varies from^100 m to 1000 m.and maximum channel depth reaches up to^35 m.Comparison of quantitative and qualitative morphologic results of different phases of incisions suggest that Phase-2 channels had^33%more mean bank full discharge than that of the Phase-3 channels.Phase-2 incisions had been carved in higher hydraulic energy condition as compared to Phase-3 incisions implying that the Indian summer monsoon was better during formative stages of Phase-2 incisions.
文摘Mg-7.6% Al （in mass fraction） alloy matrix composites reinforced with different volume fractions of nano- crystalline Al3Cas particles were synthesized by powder metallurgy, and the effect of the volume fraction of reinforcement on the mechanical properties was studied. Room temperature compression test reveals considerable improvement on mechanical properties as compared to unreinforced matrix. The compressive strength increases from 683 MPa for unre- inforced alloy matrix to about 767 and 823 MPa for the samples having 20 and 40 vol% of reinforcement, respectively, while retaining appreciable plastic deformation ranging between 12 and 24%. The specific strength of the composites increased significantly, demonstrating the effectiveness of the low-density AlaCas reinforcement.
