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Hydromagnetic oscillatory Couette flow in rotating system with induced magnetic field

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Applied Mathematics and Mechanics(English Edition) 2014年第10期35卷 1331-1344页

作者： G.s.sETH s.M.HUssAIN s.sarkar Department of Applied Mathematics Indian School of Mines Department of Mathematics O.P.Jindal Institute of Technology

This paper presents a study of hydromagnetic Couette flow of an incompress- ible and electrically conducting fluid between two parallel rotating plates, one of which is oscillating in its own plane. A uniform transverse magnetic field is used, and the induced magnetic field is taken into account. The exact solution to the governing equations is obtained in a closed form. The solution to the problem in the case of vanishing and small finite magnetic Prandtl numbers is also derived from the general solution. The asymp- totic behavior of the solution for large values of the frequency parameter is analyzed to gain some physical insights into the flow pattern. Expressions for the shear stress at both the oscillatory and stationary plates due to primary and secondary flows and mass flow rate in the primary and secondary flow directions are also obtained. The results of the fluid velocity and the induced magnetic field are presented. The shear stresses on the plates due to the primary and secondary flows and the corresponding mass flow rates are presented in a tabular form.

关键词： magnetic interaction parameter Ekman number frequency parameter,hydromagnetic stokes-Ekman boundary layer magnetic diffusion boundary layer

Landslide Hazard Zonation Mapping and Comparative Analysis of Hazard Zonation Maps

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Journal of Mountain science 2008年第3期5卷 232-240页

作者： s.sarkar R.Anbalagan Central Building Research Institute Roorkee Indian Institute of Technology Roorkee

Landslide hazard zonation mapping at regional level of a large area provides a broad trend of landslide potential zones. A macro level landslide hazard zonation for a small area may provide a better insight into the landslide hazards. The main objective of the present work was to carry out macro landslide hazard zonation mapping on 1:50,000 scale in an area where regional level zonation mapping was conducted earlier. In the previous work the regional landslide hazard zonation maps of srinagar-Rudraprayag area of Garhwal Himalaya in the state of Uttarakhand were prepared using subjective and objective approaches. In the present work the landslide hazard zonation mapping at macro level was carried out in a small area using a Landslide Hazard Evaluation Factor rating scheme. The hazard zonation map produced by using this technique classifies the area into relative hazard classes in which the high hazard zones well correspond with high frequency of landslides. The results of this map when compared with the regional zonation maps prepared earlier show that application of the present technique identified more details of the hazard zones, which are broadly shown in the earlier zonation maps.

关键词：滑坡地带危险地带地质分层地质学

电火花线切割5083Al合金的实验研究和参数优化(英文)

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Transactions of Nonferrous Metals society of China 2014年第2期24卷 373-379页

作者： G.sELVAKUMAR G.sORNALATHA s.sarkar s.MITRA Department of Mechanical Engineering National Engineering CollegeK.R. Nagar 628503 Tamilnadu India Mechanical Engineering Department SCAD College of Engineering & TechnologyCheranmahadevi 627414 Tamilnadu India Production Engineering Department Jadavpur UniversityKolkata 700032 India

通过实验分析,优化电火花线切割5083 Al合金的工艺参数。基于Taguchi优化法,将脉宽、脉间、峰电流和线张力作为输入参数进行了系列实验。将表面粗糙度和切割速度作为响应,基于信噪比,测定了输入参数对响应的影响。通过Taguchi优化方法,... 详细信息

通过实验分析,优化电火花线切割5083 Al合金的工艺参数。基于Taguchi优化法,将脉宽、脉间、峰电流和线张力作为输入参数进行了系列实验。将表面粗糙度和切割速度作为响应,基于信噪比,测定了输入参数对响应的影响。通过Taguchi优化方法,得到了最大切割速度和最小表面粗糙度的最佳加工参数。再采用附加的模型预测可能的加工组合。最后,通过使用Pareto优化法,得到一个简明的工艺参数表。

关键词：丝电火花加工铝合金 Taguchi方法附加模型优化 Pareto优化

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斜坡不稳定性分类的统计模型

世界地质 1997年第1期16卷 83-88页

作者： srideviJadi s.sarkar 杨健

给出了对一给定地区滑坡灾害进行评价的可靠的统计模型。该模型是在信息论和回归分析的基础上建立的。信息论是概率论的一个分支，根据该理论，最具意义的特征因素是不可预见的；而回归分析则是基于简单的统计理论。两种统计预测方法均... 详细信息

给出了对一给定地区滑坡灾害进行评价的可靠的统计模型。该模型是在信息论和回归分析的基础上建立的。信息论是概率论的一个分支，根据该理论，最具意义的特征因素是不可预见的；而回归分析则是基于简单的统计理论。两种统计预测方法均应用于斜坡的不稳定性分析，并对两种结果进行了对比。另外，编制了应用于滑坡灾害评价的Fortran77程序，该程序考虑了影响斜坡不稳定性的各种因素，以及研究区历史上曾经发生滑坡的情况，同时该程序也可以计算研究区的信息值和回归值，并根据不稳定性等级对研究区进行分区。文中给出了奥克南达山谷一个66km2地区的滑坡灾害评价实的。分析中所考虑的影响因素为坡角、坡高、岩石类型以及地质构造等。根据上述两种方法得出的分析结果，分别绘制成滑坡灾害分区图，并进行比较。

关键词：斜坡不稳定性分类统计模型滑坡

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sO_3对铜冶炼厂工艺设备腐蚀的影响

中国有色冶金 1984年第8期23卷 37-40,30页

作者： s.sarkar 宋修治

本文就铜冶炼过程烟气中sO_3、H_2sO_4的生成和硫酸冷凝,对设备的影响,作了讨论。气相中的水汽、sO_2和H2sO_4的浓度与温度的关系,气流中H_2sO_4蒸汽的露点,以及过程中设备腐蚀等也作了叙述。通过这些研究,提供了一些设想和建议。

关键词： sO3 硫酸硫化合物操作条件设备腐蚀铜冶炼厂停留时间硫酸露点饱和曲线临界区

GIs Based spatial Data Analysis for Landslide susceptibility Mapping

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Journal of Mountain science 2008年第1期5卷 52-62页

作者： s.sarkar scientist D.P.Kanungo A.K.Patra Pushpendra Kumar Central Building Research Institute Roorkee-247667India scientist Central Building Research InstituteRoorkee-247667India Research Fellow Central Building Research InstituteRoorkee-247667India

Landslide susceptibility map delineates the potential zones for landslides occurrence. The paper presents a statistical approach through spatial data analysis in GIs for landslide susceptibility mapping in parts of sikkim Himalaya. six important causative factors for landslide occurrences were selected and corresponding thematic data layers were prepared in GIs. Topographic maps,satellite image,field data and published maps constitute the input data for thematic layer preparation. Numerical weights for different categories of these factors were determined based on a statistical approach and the weighted thematic layers were integrated in GIs environment to generate the landslide susceptibility map of the area. The landslide susceptibility map classifies the area into five different landslide susceptible zones i.e.,very high,high,moderate,low and very low. This map was validated using the existing landslide distribution in the area.

关键词：地理信息系统山崩磁化系数分析方法

双能CT小肠成像碘密度评价克罗恩病活动性炎症:与组织病理学分析的比较

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国际医学放射学杂志 2021年第6期 736-736页

作者： B.Dane s.sarkar M.Nazarian H.Galitzer T.O'Donnell F.Remzi 万怡轩

研究证明与临床标志物炎症相比,双能CT小肠成像(DECTE)可用于描述克罗恩病的活动情况,但尚未有研究与组织病理学标本进行比较。目的比较同一克罗恩病病人

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Early Paleozoic basement diorite of arc-magmatism from Kutch basin, Western India

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Acta Geochimica 2024年第2期43卷 296-307页

作者： Piyush Gupta sandeep singh shakti singh Rathore Argha Narayan sarkar Geochronology Laboratory KDMIPEOil and Natural Gas Corporation Ltd.9Kaulagarh RoadDehradun 248195India Department of Earth sciences Indian Institute of TechnologyRoorkee 247667India

In this study,we report for theﬁrst time an Early Palaeozoic basement diorite from the drilled well Nirona-A in the Banni Half-Graben of the Kutch basin,western India.The 40Ar–39Ar dates provided a plateau age of 441.84±2.66 Ma and another pseudo plateau of 441.28±5.82 to 388.08±16.65 Ma for the basement diorite.These ages constrain the basement formation age to the Late Ordovician-Early silurian period.The obtained basement ages are correlatable with the later part of Cambro-Ordovician alkaline magmatism that has been reported from the Huqf area in Central Oman,whereas their lithological and petrographic correlativity with base-ment diorites occurring in the Dinsi Body of Nagar Parkar igneous complex in Pakistan can also be envisaged.The geochemical studies characterized the diorite with enrich-ment of LILE(Rb,Ba,and K)and LREE(La,Ce,Nd),strong depletion of HFsE(Nb,sr,P,and Ti),along with weakly negative Eu anomalies.The geochemical signatures indicate their petrogenetic afﬁliation with mantle-derived magmas,as well as their tectonic setting to be arc-related,having post-collisional continental-arc type afﬁnity.The*440 Ma basement of Kutch,therefore,appears to rep-resent the later thermal event associated with the reworked Neoproterozoic subduction-related suite from Greater India’s northwest edge,which has implications for Gond-wana assembly in the northwest Indian subcontinent.

关键词： Kutch basin 40Ar–39Ar ages Early palaeozoic basement Continental-arc magmatism Calc-alkaline magmatism

Maser radiation from collisionless shocks: application to astrophysical jets

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High Power Laser science and Engineering 2019年第1期7卷 120-127页

作者： D.C.speirs K.Ronald A.D.R.Phelps M.E.Koepke R.A.Cairns A.Rigby F.Cruz R.M.G.M.Trines R.Bamford B.J.Kellett B.Albertazzi J.E.Cross F.Fraschetti P.Graham P.M.Kozlowski Y.Kuramitsu F.Miniati T.Morita M.Oliver B.Reville Y.sakawa s.sarkar C.spindloe M.Koenig L.O.silva D.Q.Lamb P.Tzeferacos s.Lebedev G.Gregori R.Bingham Department of Physics SUPA University of Strathclyde Department of Physics West Virginia University school of Mathematics and statistics University of St.Andrews Department of Physics University of Oxford GoLP/Instituto de Plasmas e Fus?u Nuclear Instituto Superior T'ecnico Universidade de Lisboa sTFC Rutherford Appleton Laboratory Laboratoire pour l’Utilisation de Lasers Intenses UMR7605 CNRS CEA Universit'e Paris VI Ecole Polytechnique Departments of Planetary sciences and Astronomy University of Arizona AWE Aldermaston Reading West Berkshire Department of Physics National Central University Institute of Laser Engineering Osaka University school of Mathematics and Physics Queen’s University Belfast Department of Astronomy and Astrophysics University of Chicago Imperial College London

This paper describes a model of electron energization and cyclotron-maser emission applicable to astrophysical magnetized collisionless shocks. It is motivated by the work of Begelman, Ergun and Rees [Astrophys. J. 625, 51(2005)] who argued that the cyclotron-maser instability occurs in localized magnetized collisionless shocks such as those expected in blazar jets. We report on recent research carried out to investigate electron acceleration at collisionless shocks and maser radiation associated with the accelerated electrons. We describe how electrons accelerated by lower-hybrid waves at collisionless shocks generate cyclotron-maser radiation when the accelerated electrons move into regions of stronger magnetic fields. The electrons are accelerated along the magnetic field and magnetically compressed leading to the formation of an electron velocity distribution having a horseshoe shape due to conservation of the electron magnetic moment. Under certain conditions the horseshoe electron velocity distribution function is unstable to the cyclotron-maser instability [Bingham and Cairns, Phys. Plasmas 7, 3089(2000); Melrose, Rev. Mod. Plasma Phys. 1, 5(2017)].

关键词： laboratory astrophysics plasma physics particle acceleration plasma-wave instabilities