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Trace fossil evidences of an Early Miocene paleoseismic event and depositional regime change from the Kutch(Kachchh) Basin

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Journal of Palaeogeography 2024年第1期13卷 165-180页

作者： Ayush Srivastava Sudipta Dasgupta Krishanu Chatterjee Mohuli Das bombay Ichnos Research Group Department of Earth SciencesIndian Institute of Technology Bombay(lIT Bombay)PowaiMumbaiMaharashtra400076India

Unconsolidated siliciclastic sediments can undergo post-burial deformation, which leads to the formation of distinctive sedimentary structures, known as soft-sediment deformation structures(SSDS). The presence of a series of sand volcanoes confined to a particular lithostratigraphic horizon can represent a paleoseismic activity and, thereby, exemplifies the concept of “seismite”. The Kutch Basin has been a tectonically active region since the initiation of eastern Gondwana rifting followed by a tectonic inversion during the Cenozoic due to the collision of the Indian and Eurasian plates. A stratum-bound series of sand volcanoes belonging to the Khari Nadi Formation(KNF) is exposed along the banks of Khari River. They separate the shallow marine deposits below and non-marine deposits above with their characteristic marine and paleosol trace fossil suites, respectively. Although a seismogenic origin has been much debated for the SSDS,the ichnofabric analysis of the sand-volcano-bearing stratum unequivocally points toward such an origin under a shallow seafloor condition. In addition to the sedimentary regime change from an open shallow-marine setting to a continental depositional environment concomitant with basinal uplift, the behavior of the burrowing crustaceans testifies to a syn-depositional development of a fault network associated with the fluidization, sand volcanism, and the resilience of the trace-producers in surviving those processes until the sedimentary regime change in the overlying strata. Although the ichno-sedimentological evidence apparently differs from the previous works that proposed a continuous base-level rise from the beginning of deposition of the Khari Nadi Formation up to the middle part of the overlying Chhasra Formation, the paleoseismic activity,its ichnologic signature, and the depositional regime change refer to a higher-resolution(i.e., lower-order)sequence-stratigraphic change causing a short-duration regression within a longer-durat

关键词： Sand volcano Seismite Ichnology Khari Nadi Formation Kutch Basin Kachchh Basin

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Ward identities under the frame transformations in curved space-time

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Communications in Theoretical Physics 2024年第9期76卷 109-119页

作者： Susobhan Mandal Department of Physics Indian Institute of Technology Bombay

Scalar-tensor theories of gravity are considered to be competitors to Einstein's theory of general relativity for the description of classical gravity, as they are used to build feasible models for cosmic inflation. These theories can be formulated both in the Jordan and Einstein frame, which are related by a Weyl transformation with a field transformation, known together as a frame transformation. These theories formulated in the above two frames are often considered to be equivalent from the point of view of classical theory. However, this is no longer true from the quantum field theoretical perspective. In the present article, we show that the Ward identities derived in the above two frames are not connected through the frame transformation. This shows that the quantum field theories formulated in these two frames are not equivalent to each ***, this inequivalence is also shown by comparing the effective actions derived in these two frames.

关键词： curved spacetime frame transformations ward identities

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Snow and regolith albedo variations using CRISM data at McMurdo crater,Mars

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Earth and Planetary Physics 2024年第2期8卷 338-355页

作者： Sehajpal Singh Deepak Singh Centre of Studies in Resources Engineering Indian Institute of Technology BombayMumbaiIndia

The cryosphere component provides the most reliable and insightful indications of any planet’s climate *** data from the Compact Reconnaissance Imaging Spectrometer for Mars(CRISM),we develop a novel approach to determining the broadband Visible and Near Infrared(VNIR)albedo of the Martian *** study focuses on albedo changes in the McMurdo crater,part of Mars’s south polar layer *** compare seasonal and interannual variations of the McMurdo surface albedo before,during,and after the Global Dust Storm(GDS)of Martian Year(MY)*** the seasons progressed from spring to summer,the mean albedo in MY 32 and 34 plunged by over 40%,by about 35%in MY 33,and by slightly more than 30%in MY *** interannually,however,mean albedo values within both seasons(spring and summer)exhibited no significant differences in those same ***,interannual albedo difference maps reveal albedo variation of more than±0.3 in certain regions of the *** only snow-covered pixels,interannual albedo differences suggest that Mars dust had a pervasive impact on Mars’s *** in maximum and minimum albedo values as high as 0.5 were observed,depending upon differences in the dust levels in Martian snow/*** maximum and the minimum snow albedo values were lowest in MY 34,indicating the effect of the intense dust storm event that *** average snow albedo decreased from 0.45 in MY 32 to 0.40 in MY 33 and to 0.33 in MY 34,and then rose back to 0.40 in MY *** trajectory suggests a temporary deposition of dust,partially reversed after the GDS by self-cleaning mechanisms(local aeolian process and CO_(2)sublimation/deposition cycle).

关键词： Mars Martian ice albedo dust storm Mars surface Martian climate

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Evaluation of building energy demand forecast models using multi-attribute decision making approach

Energy and Built Environment

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Energy and Built Environment 2024年第3期5卷 480-491页

作者： Nivethitha Somu Anupama Kowli Department of Electrical Engineering Indian Institute of Technology-BombayMumbaiMaharashtra 400076India

With the existence of several conventional and advanced building thermal energy demand forecast models to improve the energy efficiency of buildings,it is hard to find an appropriate,convenient,and efficient *** based on statistical indexes(MAE,RMSE,MAPE,etc.)that characterize the accuracy of the forecasts do not help in the identification of the efficient building thermal energy demand forecast tool since they do not reflect the efforts entailed in implementation of the forecast model,i.e.,data collection to production/use ***,this work presents a Gini Index based Measurement of Alternatives and Ranking according to COmpromise Solution(GI-MARCOS),a hybrid Multi Attribute Decision Making(MADM)approach for the identification of the most efficient building energy demand forecast ***-MARCOS employs(i)GI based objective weight method:assigns meaningful objective weights to the attributes in four phases(1:pre-processing,2:implementation,3:post-processing,and 4:use phase)thereby avoiding unnecessary biases in the expert’s opinion on weights and applicable to domains where there is a lack of domain expertise,and(ii)MARCOS:provides a robust and reliable ranking of alternatives in a dynamic environment.A case study with three alternatives evaluated over three to six attributes in four phases of implementation(pre-processing,implementation,post-processing and use)reveals that the use of GI-MARCOS improved the accuracy of alternatives MLR and BM by 6%and 13%,***,additional validations state that(i)MLR performs best in Phase 1 and 2,while ANN performs best in Phase 3 and 4 with BM providing a mediocre performance in all four phases,(ii)sensitivity analysis:provides robust ranking with interchange of weights across phases and attributes,and(iii)rank correlation:ranks produce by GI-MARCOS has a high correlation with GRA(0.999),COPRAS(0.9786),and ARAS(0.9775).

关键词： Building energy demand Multi-attribute decision making Objective weights Forecast models Sensitivity analysis

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Confinement effect on CO_(2)and CH_(4)permeability in shale

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Energy Geoscience 2024年第1期5卷 256-263页

作者： Vikram Vishal Tuli Bakshi Computational and Experimental Geomechanics Laboratory Department of Earth SciencesIndian Institute of Technology BombayMumbai400076India National Centre of Excellence in Carbon Capture and Utilization Indian Institute of Technology BombayMumbai400076India

Gas flow in shales follows a number of physical mechanisms that include Knudsen diffusion,Darcy flow,and adsorption in the matrix and micro *** aim of the study is to resolve the interplay of gas transport in these media at increased effective stress as well as net pore *** this research,we investigated the nature of gas transport in the matrix of shale by sending He,CH_(4)and CO_(2)gases through a transient upstream pressure pulse decay instrument.A series of experiments were conducted at constant pore pressures and a gradually increasing confining *** same study was done in three different scenarios,injecting He,CO_(2)and CH_(4).At a constant pore pressure,gas permeability appears to decrease with an increasing confining pressure and effective *** increasing effective stress,the slip factor also decreases along with the *** decrease in slip could be attributed to prestressing,that is likely to create new *** the three purged gases,permeability of shale to CH_(4)is the highest,and that to CO_(2)is the lowest owing to its high *** permeability of CH_(4)against He,could be attributed to the dual transport mechanism.

关键词： Energy Porous media Gas transport Effective stress

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Assessing the Viability of Gandhar Field in India’s Cambay Basin for CO_(2) Storage

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哈尔滨工程大学学报（英文版） 2024年第3期23卷 529-543页

作者： Vikram Vishal Somali Roy Yashvardhan Verma Bharath Shekar Department of Earth Sciences Indian Institute of Technology BombayMumbai 400076India National Centre of Excellence in Carbon Capture and Utilization Indian Institute of Technology BombayMumbai 400076India

Our research is centered on the Gandhar oil field, which was discovered in 1983, where daily oil production has declined significantly over the years. The primary objective was to evaluate the feasibility of carbon dioxide(CO_(2)) storage through its injection into the siliciclastic reservoirs of Ankleshwar Formation. We aimed to obtain high-resolution acoustic impedance data to estimate porosity employing model-based poststack seismic inversion. We conducted an analysis of the density and effective porosity in the target zone through geostatistical techniques and probabilistic neural networks. Simultaneously, the work also involved geomechanical analysis through the computation of pore pressure and fracture gradient using well-log data, geological information, and drilling events in the Gandhar field. Our investigation unveiled spatial variations in effective porosity within the Hazad Member of the Ankleshwar Formation, with an effective porosity exceeding 25% observed in several areas, which indicates the presence of well-connected pore spaces conducive to efficient CO_(2) migration. Geomechanical analysis showed that the vertical stress(Sv) ranged from 55 MPa to 57 MPa in Telwa and from 63.7 MPa to 67.7 MPa in Hazad Member. The pore pressure profile displayed variations along the stratigraphic sequence, with the shale zone, particularly in the Kanwa Formation, attaining the maximum pressure gradient(approximately 36 MPa). However, consistently low pore pressure values(30-34 MPa) considerably below the fracture gradient curves were observed in Hazad Member due to depletion. The results from our analysis provide valuable insights into shaping future field development strategies and exploration of the feasibility of CO_(2) sequestration in Gandhar Field.

关键词： Carbon capture and storage Reservoir characterization Seismic inversion Geomechanics CO_(2)storage CO_(2)enhancing oil recovery

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Geomorphic signatures and active tectonics in western Saurashtra,Gujarat,India

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Geodesy and Geodynamics 2024年第1期15卷 82-99页

作者： Bikramaditya Mondal Mery Biswas Soumyajit Mukherjee Mohamedharoon A.Shaikh Department of Earth Sciences Indian Institute of Technology BombayMumbai 400076MaharashtraIndia Department of Geography Presidency UniversityKolkata 700073West BengalIndia

Active tectonics in an area includes ongoing or recent geologic *** paper investigates the tectonic influence on the subsidence,uplift and tilt of western Saurashtra through morphotectonic analysis of ten watersheds along with characteristics of relief and drainage *** 7-9 to the north(N)are tectonically active,which can be linked with the North Kathiawar Fault System(NKFS)and followed by watersheds 6,10,1,4 and ***-length gradient index and sinuosity index indicate the effect of tectonic events along the master streams in watersheds *** R^(2)values of the linear curve fit for watershed 7 indicate its master stream is much more tectonically active than the *** R^(2)curve fitting model and earthquake magnitude/depth analysis confirm the region to be *** reactivation of the NKFS most likely led to the vertical movement of western Saurashtra.

关键词： Active tectonics Geomorphology Western Saurashtra Archeology North kathiawar fault system

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Circum-Indian Holocene sea-level database:A repository of distinct relative sea-level plots across the Indian Peninsula

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Journal of Palaeogeography 2024年第1期13卷 1-17页

作者： Shradha Menon Pankaj Khanna Santanu Banerjee REEFS Lab Department of Earth SciencesIIT GandhinagarPalajGandhinagarGujarat382355India Department of Earth Sciences IIT BombayPowaiMumbai400076India

The Indian Peninsula is one of the most well-studied regions for Holocene sea-level fluctuations in the world, however, standardized relative sea-level datasets are missing. This study provides an archive of sealevel indicators(n = 162, 20 locations) along the western and the eastern sides of the peninsula, that have been used to develop Relative Sea Level(RSL) plots. Each dated sea-level indicator is recalibrated for its elevation based on tidal and tectonic correction, as well as age with reservoir correction, and have been separated into six zones based on coastal geomorphology and number of datasets. The database spans throughout the Holocene and covers sea-level depth/elevations from-45 m to +5 m from mean sea-level(MSL). Approximately 90 % of the dataset range from 8 ka to the present day. The first transgression is highly variable and identified between 8.5-8 ka BP in Gujarat(Zone 1), ~ 5.5 ka BP in Maharashtra(Zone 2), between 8 and 7 ka BP in Tamil Nadu(Zone 4) and between 8 and 7.5 ka BP in the Bengal coasts(Zone 6). No transgression above present sea-level is observed along Andhra Pradesh(Zone 5)(no data for Kerala-Zone 3).Further, Zones 1, 2, 4 and 6 show a strong uplift component(tectonic), whereas Zone 5 exhibits subsidence during the Holocene(Zone 3-insufficient data). Based on these findings, and given the region's coastal topography and tidal components, Zones 6 and 1 will likely undergo the largest coastal inundation, followed by Zones 5, 4, 2, and 3. These insights are critical in planning future coastal inundation measures across the Indian Peninsula.

关键词： Indian ocean Terraces Relative sea level curve Holocene Arabian sea Bay of Bengal

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Aerodynamics of a Tandem-Bladed Axial Compressor Rotor under Circumferential Distortion at Different Rotational Speeds

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Journal of Thermal Science 2024年第4期33卷 1340-1356页

作者： Amit KUMAR Jerry T.JOHN A.M.PRADEEP R.A.DAKKERMANS Dragan KOZULOVIC Department of Aerospace Engineering Indian Institute of Technology BombayMumbai400076India Department of Automotive and Aeronautical Engineering Hamburg University of Applied Sciences20099HamburgGermany Institute of Jet Propulsion Bundeswehr University Munich85577NeubibergGermany

For most aircraft engines,inflow distortion is *** distortion is known to degrade the aerodynamic performance and stable operating limits of a *** rotor configuration is an arrangement that effectively controls the growth of the boundary layer over the suction surface of the ***,a higher total pressure rise can be achieved through this unconventional design approach involving the splitting of the blade into forward and aft *** is expected that the effect of inlet flow distortion would be more severe for a tandem-rotor design due to the greater flow turning inherent in such ***,this aspect needs to be thoroughly *** present study discusses the effect of circumferential distortion on the tandem-rotor at different rotational ***-annulus RANS simulations using ANSYS CFX are used in the present *** performance of the rotor at a particular flow coefficient and different rotational speeds is *** total pressure and efficiency are observed to drop at lower mass flow rates under the influence of circumferential *** loss region in each blade passage is mainly associated with the blade wake,tip leakage vortex,secondary flow,and boundary ***,their contribution varies from passage to passage,particularly in the distorted *** the lower span,the wake width is found to be higher than that at a higher *** to the redistribution of the mass flow,the circumferential extent reduces at a higher *** the undistorted sector,the strength of the tip leakage vortex is significantly higher at the design rotational speed than at lower *** distortion near the tip region promotes an early vortex breakdown even at the design operating *** adversely affects the total pressure,efficiency,and stall *** clean flow conditions,this phenomenon is only observed near the stall *** the design operating condition,the breakdown of the forward rotor tip l

关键词： tandem rotor circumferential distortion loss tip leakage vortex vortex breakdown diffusion factor aerodynamics of compressor blade

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印度Cambay盆地Gandhar油田的CO2封存可行性评估（英文）

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Journal of Marine Science and Application 2024年第3期23卷 529-543页

作者： Vikram Vishal Somali Roy Yashvardhan Verma Bharath Shekar Department of Earth Sciences Indian Institute of Technology Bombay National Centre of Excellence in Carbon Capture and Utilization Indian Institute of Technology Bombay

Our research is centered on the Gandhar oil field, which was discovered in 1983, where daily oil production has declined significantly over the years. The primary objective was to evaluate the feasibility of carbon dioxide（CO2） storage through its injection into the siliciclastic reservoirs of Ankleshwar Formation. We aimed to obtain high-resolution acoustic impedance data to estimate porosity employing model-based poststack seismic inversion. We conducted an analysis of the density and effective porosity in the target zone through geostatistical techniques and probabilistic neural networks. Simultaneously, the work also involved geomechanical analysis through the computation of pore pressure and fracture gradient using well-log data, geological information, and drilling events in the Gandhar field. Our investigation unveiled spatial variations in effective porosity within the Hazad Member of the Ankleshwar Formation, with an effective porosity exceeding 25% observed in several areas, which indicates the presence of well-connected pore spaces conducive to efficient CO2migration. Geomechanical analysis showed that the vertical stress（Sv） ranged from 55 MPa to 57 MPa in Telwa and from 63.7 MPa to 67.7 MPa in Hazad Member. The pore pressure profile displayed variations along the stratigraphic sequence, with the shale zone, particularly in the Kanwa Formation, attaining the maximum pressure gradient（approximately 36 MPa）. However, consistently low pore pressure values（30-34 MPa） considerably below the fracture gradient curves were observed in Hazad Member due to depletion. The results from our analysis provide valuable insights into shaping future field development strategies and exploration of the feasibility of CO2sequestration in Gandhar Field.

关键词： Carbon capture and storage Reservoir characterization Seismic inversion Geomechanics CO2 storage CO2 enhancing oil recovery NEURAL-NETWORK ATTRIBUTES

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