Preface     

Pitambar Gautam  Teiji Watanabe  Hiroshi Nishi  Tetsuzo Yasunari 《Island Arc》2005,14(4):295-296

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Kinematics-Based Mathematical Model for Deforming Thrust Wedges     

Matty Mookerjee  Gautam Mitra 《Mathematical Geosciences》2008,40(3):249-275

Given the wealth of data concerning the kinematics of deforming fold-thrust belts (FTBs), first-order generalizations about how the major strain components vary within a deforming thrust wedges are considered. These generally observed strain patterns are used to constrain a general, kinematics-based, FTB-wedge model. We considered five strain components within a deforming thrust sheet: (1) thrust-parallel simple shear, (2) horizontal contractional strain, (3) thrust-normal reaction strain, (4) gravitational strain, and (5) a lateral confining boundary condition. After making assumptions about how these strain components vary within a model FTB-wedge, the incremental deformation matrix can be calculated for any given point within the deforming wedge. Thus, the material path of a given marker can be determined and an initially spherical marker’s strain path can be calculated as it moves through the deforming wedge. Furthermore, by illustrating various kinematic parameters of many initially spherical markers (for example, Flinn’s k-value, incremental octahedral shear strain, transport-perpendicular stretch), we have assembled representations of the kinematic properties of the entire model wedge. By including a flat-ramp-flat fault surface geometry for the model wedge, we are able to examine the kinematic effects of this relatively common structural geometry. Within the fault ramp segment there are greater incremental strain magnitudes, out-of-the-plane motion, and flattening strains. Additionally, data from this model suggests that gravitational strains potentially have a significant effect on the strain distribution within a deforming thrust wedge. M. Mookerjee is formerly Matthew Strine.  相似文献   

Discussion of the paper “Na and Cr contents in clinopyroxenes from peridotites: a possible discriminant between ‘sub-continental’ and ‘sub-oceanic’ mantle” by J. Kornprobst, D. Ohnenstetter and M. Ohnenstetter     

Gautam Sen 《Earth and Planetary Science Letters》1982,60(3):452-454

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Study of landform control over land utilisation pattern     

Seelan S. Kumar  G. Ch. Chennaiah  N. C. Gautam 《Journal of the Indian Society of Remote Sensing》1983,11(1):49-53

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喜马拉雅碰撞造山过程：变质地质学视角   总被引：1，自引：0，他引：1  

王佳敏  吴福元  张进江  Gautam Khanal  杨雷 《地质学报》2022,96(9):3128-3157

本文从变质地质学视角出发，介绍了喜马拉雅造山带的研究意义、地质概况和近年来作者在喜马拉雅碰撞造山过程研究中的进展。喜马拉雅造山带是威尔逊旋回中陆陆碰撞造山带的典型代表，从中揭示的大陆碰撞造山过程、规律及效应，可为探索地球从古至今的碰撞造山带演化研究所借鉴。其中，大陆碰撞造山机制的研究是其核心内容。大陆碰撞造山机制存在临界楔和隧道流两种端元模型之争，其分别对造山带核部高级变质岩折返的P T t轨迹和时空演化序列进行了不同的预测。上述争议可通过研究喜马拉雅核部高级变质岩（高喜马拉雅）的P T t轨迹和折返过程来限定，据此可将喜马拉雅碰撞造山过程划分为三个演化阶段。阶段一：60～40 Ma，软碰撞期，造山带地壳加厚至约40 km并发生小规模部分熔融，这些早期地壳加厚记录大多已被剥蚀，零星保存于前陆飞来峰和北喜马拉雅片麻岩穹隆中；喜马拉雅山从海平面以下抬升至>1000 m。阶段二：40～16 Ma，硬碰撞期，造山带地壳加厚至60～70 km，发生大规模高级变质和深熔作用，高喜马拉雅内部的三个次级岩片沿着“原喜马拉雅逆冲断层”、“高喜马拉雅逆冲断层”、“主中央逆冲断层”顺序式向南挤出，形成了现今喜马拉雅造山带的核部主体，地壳堆叠使喜马拉雅山快速隆升至≥5000 m。阶段三：16～0 Ma，晚碰撞期，造山带山根榴辉岩化发生局部拆沉，但大陆汇聚仍在持续、造山带尚未发生垮塌，小喜马拉雅折返、前陆盆地形成，喜马拉雅山达到和维持现今平均高度~6000 m。因此，喜马拉雅生长过程的一级次序是顺序式向南扩展的，受控于临界楔模型，而隧道流只起次级作用。山根深部热流过程对造山带的地壳结构和地表高程有巨大的改造作用。未来对喜马拉雅造山带的变质地质学研究可能存在以下几个关键科学问题：① 喜马拉雅极端变质作用与重大碰撞造山事件的关联；② 喜马拉雅稀有金属成矿与接触变质作用的关联；③ 喜马拉雅变质脱碳作用与大陆碰撞带深部碳循环和通量。  相似文献   

Improving the performance of genetic algorithms for land-use allocation problems     

Jonas Schwaab  Kalyanmoy Deb  Erik Goodman  Sven Lautenbach  Maarten J. van Strien  Adrienne Grêt-Regamey 《International journal of geographical information science》2018,32(5):907-930

Multi-objective optimization can be used to solve land-use allocation problems involving multiple conflicting objectives. In this paper, we show how genetic algorithms can be improved in order to effectively and efficiently solve multi-objective land-use allocation problems. Our focus lies on improving crossover and mutation operators of the genetic algorithms. We tested a range of different approaches either based on the literature or proposed for the first time. We applied them to a land-use allocation problem in Switzerland including two conflicting objectives: ensuring compact urban development and reducing the loss of agricultural productivity. We compared all approaches by calculating hypervolumes and by analysing the spread of the produced non-dominated fronts. Our results suggest that a combination of different mutation operators, of which at least one includes spatial heuristics, can help to find well-distributed fronts of non-dominated solutions. The tested modified crossover operators did not significantly improve the results. These findings provide a benchmark for multi-objective optimization of land-use allocation problems with promising prospectives for solving complex spatial planning problems.  相似文献   

A comparative assessment of Kalpana-1 and MISR cloud tracked winds over the Indian Ocean region     

S. K. Deb  Inderpreet Kaur  C. M. Kishtawal  P. K. Pal 《Theoretical and Applied Climatology》2015,121(3-4):425-443

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Future projections and uncertainty assessment of extreme rainfall intensity in the United States from an ensemble of climate models     

Jianting Zhu  William Forsee  Rina Schumer  Mahesh Gautam 《Climatic change》2013,118(2):469-485

Changes in climate are expected to lead to changes in the characteristics extreme rainfall frequency and intensity. In this study, we propose an integrated approach to explore potential changes in intensity-duration-frequency (IDF) relationships. The approach incorporates uncertainties due to both the short simulation periods of regional climate models (RCMs) and the differences in IDF curves derived from multiple RCMs in the North American Regional Climate Change Assessment Program (NARCCAP). The approach combines the likelihood of individual RCMs according to the goodness of fit between the extreme rainfall intensities from the RCMs’ historic runs and those from the National Centers for Environmental Prediction (NCEP) North American Regional Reanalysis (NARR) data set and Bayesian model averaging (BMA) to assess uncertainty in IDF predictions. We also partition overall uncertainties into within-model uncertainty and among-model uncertainty. Results illustrate that among-model uncertainty is the dominant source of the overall uncertainty in simulating extreme rainfall for multiple locations in the U.S., pointing to the difficulty of predicting future climate, especially extreme rainfall regimes. For all locations a more intense extreme rainfall occurs in future climate; however the rate of increase varies among locations.  相似文献   

Seismic treatment for a maximal credible earthquake in Guwahati city area of northeast India region     

Olga Erteleva  Felix Aptikaev  Saurabh Baruah  Santanu Baruah  Sajal K. Deb  J. R. Kayal 《Natural Hazards》2014,70(1):733-753

Strong ground motion parameters for the Guwahati city area, the capital city of the state of Assam in northeast India, are examined with the help of data accrued from local as well as worldwide network. Empirical relations are proposed for the ground motion parameters as a function of earthquake magnitude, distance, fault type, source depth and velocity characteristics of medium. Seismotectonics of the study region is examined, and a maximum credible earthquake M _S ~ 8.0 is presumed from the Brahmaputra fault, the nearest source zone in the city area. Such great/major event may cause intensity of the of 9.3 with a probability of 0,95 in the Guwahati city during time interval of 500 years. Further, the design spectrum with 67 % confidence level and the synthetic three-component accelerograms are constructed. These results are much relevant and useful for structural engineering to mitigate seismic hazards in the region.  相似文献   

Shake Table Tests and Numerical Modeling of Liquefaction of Kasai River Sand     

Raj Banerjee  Sanku Konai  Aniruddha Sengupta  Kousik Deb 《Geotechnical and Geological Engineering》2017,35(4):1327-1340

As a part of the seismic safety evaluation of several bridges and other hydraulic structures located on Kasai River bed in India, the liquefaction potential of Kasai River sand is studied in 1-g shake table in laboratory and numerically using a commercial software FLAC 2D. The surface settlement, lateral spreading, predominant frequency, amplification of the ground motion and pore water pressure development in Kasai River sand in dry and liquefied states have been studied when subjected to sinusoidal motions of amplitude 0.35 g at a frequency of 2 Hz. The nonlinear curves used to represent shear strain dependency of stiffness and damping ratio of Kasai River sand are obtained from cyclic triaxial tests. Reasonably good agreement between the experimental and the numerical results is observed. It is found that the settlement and lateral spreading for the liquefied sand is 2.60 and 2.50 times than those of the sand in the dry state. The volumetric strain of the liquefied sand is found to be around 4%, which is significantly higher than 1.53% observed in the dry sand. It is observed that the amplification of the peak ground acceleration for the saturated sand is 1.08 and 1.32 times higher than that for the dry sand from theoretical and experimental results, respectively. The shear strain developed in the liquefied sand is 1.17 times more than that for dry sand. The fundamental and higher modal frequencies of dry sand are found to be 1.13, 1.117 and 1.119 times more than those for the saturated sand, respectively.  相似文献