Pullout test model for extensible reinforcement     

N. Gurung  Y. Iwao  M. R. Madhav 《国际地质力学数值与分析法杂志》1999,23(12):1337-1348

A formulation for the analysis of pullout test on highly extensible planar reinforcement is presented. The non-linear differential equation for pullout mechanism was expressed in non-dimensional form and solved numerically using the Gauss–Siedel technique. Parametric study was carried out for various ranges of relative stiffnesses, and relative bond resistances. Normalized load–displacement relations and the variations of pullout force and reinforcement displacements along the length of reinforcement are presented graphically. A method for the estimation of the interface interaction parameters from a pre-failure test is also given. The numerical predictions compare well with the available experimental pullout test results for various geotextiles, polymers and nylon geosynthetics. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Associated HI absorption in thez = 3.4 radio galaxy B2 0902 + 343 observed with the GMRT     

Poonam Chandra  Govind Swarup  Vasant K. Kulkarni  Nimisha G. Kantharia 《Journal of Astrophysics and Astronomy》2004,25(1-2):57-65

We have made observations of the as sociated HI absorption of a high redshift radio galaxy 0902+34 atz = 3.395 with the Giant Meterwave Radio Telescope in the 323 ± 1 MHz band. We find a narrow absorption line with a flux density of 11.5 mJy at a redshift of 3.397 consistent with that observed by Usonet al. (1991), Briggset al. (1993) and de Bruyn (1996). A weak broad absorption feature reported by de Bruyn (1996) has not been detected in our observations. We also place an upper limit of 4mJy(2σ) on emission line strength at the position where Usonet al. (1991) claimed to have found a narrow emission line.  相似文献   

Instruments of RT-2 experiment onboard CORONAS-PHOTON and their test and evaluation I: ground calibration of RT-2/S and RT-2/G     

Dipak Debnath  Anuj Nandi  A. R. Rao  J. P. Malkar  M. K. Hingar  T. B. Kotoch  S. Sreekumar  V. P. Madhav  Sandip K. Chakrabarti 《Experimental Astronomy》2011,29(1-2):1-25

Phoswich detectors (RT-2/S & RT-2/G) are major scientific payloads of the RT-2 Experiment onboard the CORONAS-PHOTON mission, which was launched into a polar Low Earth Orbit of around 550 km on 2009 January 30. These RT-2 instruments are designed and developed to observe solar flares in hard X-rays and to understand the energy transport processes associated with these flares. Apart from this, these instruments are capable of observing Gamma Ray Bursts (GRBs) and Cosmic diffuse X-ray background (CDXRB). Both detectors consist of identical NaI(Tl) and CsI(Na) scintillation crystals in a Phoswich combination, having the same diameter (116 mm) but different thicknesses. The normal working energy range is from 15 keV to 150 keV, but may be extendable up to ~1 MeV. In this paper, we present the RT-2/S and RT-2/G instruments and discuss their testing and calibration results. We used different radio-active sources to calibrate both detectors. The radio-active source ⁵⁷Co (122 keV) is used for onboard calibration of both instruments. During its lifetime (??3?C5 years), RT-2 is expected to cover the peak of the 24th solar cycle.  相似文献   

Instruments of RT-2 experiment onboard CORONAS�CPHOTON and their test and evaluation V: onboard software, data structure, telemetry and telecommand     

S. S. Sreekumar  P. Vinod  Essy Samuel  J. P. Malkar  A. R. Rao  M. K. Hingar  V. P. Madhav  D. Debnath  T. B. Kotoch  Anuj Nandi  S. Shaheda Begum  Sandip Kumar Chakrabarti 《Experimental Astronomy》2011,29(1-2):109-133

The onboard software and data communication in the RT-2 Experiment onboard the Coronas?CPhoton satellite is organized in a hierarchical way to effectively handle and communicate asynchronous data generated by the X-ray detectors. A flexible data handling system is organized in the X-ray detector packages themselves and the processing electronic device, namely RT-2/E, has the necessary intelligence to communicate with the three scientific payloads by issuing commands and receiving data. It has direct interfacing with the Satellite systems and issues commands to the detectors and processes the detector data before sending to the satellite systems. The onboard software is configured with several novel features like (a) device independent communication scheme, (b) loss-less data compression and (c) Digital Signal Processor. Functionality of the onboard software along with the data structure, command structure, complex processing scheme etc. are discussed in this paper.  相似文献   

Effect of Soil Disturbance on Consolidation By Prefabricated Vertical Drains Installed in a Rectangular Pattern     

D. Basu  M. Prezzi  M. R. Madhav 《Geotechnical and Geological Engineering》2010,28(1):61-77

In this paper, the effect of soil disturbance caused by installation of prefabricated vertical drains (PVDs) on the rate of consolidation is studied by two-dimensional finite element analysis. A transition zone lying between the highly disturbed smear and the undisturbed zones is considered in the analysis. The hydraulic conductivity in the transition zone is assumed to vary linearly from a low value in the smear zone to the original in situ value in the undisturbed zone. The analysis uses the actual band shape of the PVD and the rectangular shape of the unit cell. A parametric study is carried out to investigate the effects of the degree of soil disturbance, the size of the smear and the transition zones, the PVD spacing and the mandrel size and shape. Design guidelines, where the smear and transition zones are replaced by an expanded smear zone producing the same effect, are provided so that existing analytical solutions considering only the smear zone can be used for analysis and design. A comparison with experimental results shows that consideration of the transition zone is important for correct estimation of the degree of consolidation.  相似文献   

A multiwavelength view of the ISM in the merger remnant galaxy Fornax A     

Swati Pralhadrao Deshmukh  Bhagorao Tukaram Tate  Nilkanth Dattatray Vagshette  Sheo Kumar Pandey  Madhav Khushalrao Patil 《天文和天体物理学研究(英文版)》2013,(8):885-898

We present multi-wavelength imagery of the merger remnant galaxy NGC 1316 with an objective to study the dust content and its association with the other phases of the interstellar medium. Color-index maps as well as extinction maps derived for this galaxy reveal an intricate and complex dust morphology in NGC 1316, i.e. there is a prominent lane in the inner part, while at about 6-7 kpc it apparently takes the form of an arc-like pattern extending along the northeast direction. In addition to this, several other dust clumps and knots are also evident in this galaxy. The dust emission mapped using Spitzer data at 8 μm indicates even more complex morphological structures of the dust in NGC 1316. The extinction curve derived over the optical to near-IR bands closely follows the standard Galactic curve, suggesting similar properties of the dust grains. The dust content of NGC 1316, estimated from optical extinction, is ～ 2.13 105M⊙ . This is a lower limit compared to that estimated using the IRAS flux densities of ～5.17×106M⊙ and the flux densities at 24, 70 and 160 μm from MIPS ～3.2×107M⊙ . High resolution Chandra observations of this merger remnant system have provided an unprecedented view of the complex nature exhibited by the distribution of hot gas in NGC 1316, which closely matches the morphology of ionized gas and to some extent also the dust. X-ray color-color plots for the resolved sources within the optical D 25 extent of NGC 1316 have enabled us to separate them into different classes.  相似文献   

Seismic fragility of base-isolated water storage tanks under non-stationary earthquakes     

Sandip Kumar Saha  Vasant A. Matsagar  Arvind K. Jain 《Bulletin of Earthquake Engineering》2016,14(4):1153-1175

Seismic fragility curves for fixed-base and base-isolated liquid storage tanks are developed under non-stationary earthquakes, and their seismic performance are compared. The correlation between different earthquake intensity measure (IM) parameters and peak response quantities of the base-isolated liquid storage tanks are investigated. The failure criteria are chosen based on (1) the elastic buckling strength of the tank wall, which is defined in terms of critical base shear and critical overturning moment, and (2) in terms of the critical isolation displacement. The uncertainty involved is considered in the earthquake characteristics. Non-stationary earthquake ground motions are generated using Monte Carlo (MC) simulation. Influence of the isolator characteristic parameters and modeling approaches on the seismic fragility of the base-isolated liquid storage tanks is also investigated. Peak ground acceleration is found to be the well correlated IM parameter with the peak response quantities of the base-isolated liquid storage tanks. Substantial decrease in the seismic fragility of the base-isolated liquid storage tanks is observed as compared to the fixed-base tanks. Significant influence of the isolator characteristic parameters on the seismic fragility of the base-isolated liquid storage tanks are reported in the present study.  相似文献   

Dynamic Analysis of Tunnel in Soil Subjected to Internal Blast Loading     

Rohit Tiwari  Tanusree Chakraborty  Vasant Matsagar 《Geotechnical and Geological Engineering》2017,35(4):1491-1512

The present work deals with the three-dimensional nonlinear finite element (FE) analyses of the tunnel in soil subjected to internal blast loading. The analyses are performed using the coupled Eulerian–Lagrangian analysis tool in FE software Abaqus/Explicit. The soil and reinforced concrete lining are modeled using the Lagrangian elements. The explosive Trinitrotoluene (TNT) is modeled using the Eulerian elements. The stress–strain response of soil, concrete, and reinforcement are simulated using strain rate dependent Drucker–Prager plasticity, concrete damaged plasticity and Johnson–Cook (J–C) plasticity models, respectively. The pressure–volume relationship of the TNT explosive is simulated using the Jones-Wilkins-Lee equation of state. Parametric sensitivity studies have been performed for different (1) tunnel lining thicknesses, (2) explosive charge weights and (3) angles of internal friction of soil. It is observed from the results that blast induced pressure on the tunnel lining increases with the increase in charge weight. Both the lining and the surrounding soil undergo significant deformation. The deformation of the tunnel lining increases with increasing charge weight and decreases with increasing lining thickness and increasing the angle of internal friction of soil. Blast-induced velocity in soil attenuates with increasing distance from the source of the blast.  相似文献   

Deformation analysis of soft ground reinforced by columnar inclusions   总被引：20，自引：0，他引：20  

M. Alamgir  N. Miura  H.B. Poorooshasb  M.R. Madhav 《Computers and Geotechnics》1996,18(4):267-290

A simple theoretical approach to predict the deformation behaviour of soft ground reinforced by columnar inclusions such as stone columns./granular piles, sand compaction piles, lime or cement columns, etc., is presented in this paper. The analysis is performed based on the deformation properties of the column material and the surrounding soil. The interaction shear stresses between the column and the surrounding soil are considered to account for the stress transfer between the column and the soil. The solution is obtained by imposing compatibility between the displacements of the column and the soil for each element of the column-soil system. Numerical evaluations are made for a range of parameters to illustrate the influence of various parameters on the predictions. The proposed method is verified with finite element analysis and a reasonable agreement is obtained between the predictions.  相似文献   

Storm waves in the Canadian Atlantic: A numerical simulation     

Madhav L. Khandekar 《Natural Hazards》1994,9(1-2):125-153

The Grand Banks and the Scotian Shelf regions of the Canadian Atlantic often experience strong winds and high waves associated with the passage of intense storms during the winter months of December to March. These storm waves are identified as a major hazard to shipping, offshore exploration and other marine activities in eastern Canada.In this study, an operational spectral ocean wave model has been used to simulate sea-states associated with selected storm events in the Canadian Atlantic. The wave model operates on a grid (with grid spacing of about 111 km) which covers a major portion of the north Atlantic. A nested fine grid (with grid spacing of about 37 km) has been designed which covers the shelf regions of the Canadian Atlantic. The model employs deep-water physics over the coarse grid while over the fine grid shallow-water processes as represented by wave refraction, wave shoaling, bottom friction and wave number scaling are included. The wave model also includes, as an optional package, the third-generation source terms as represented by the nonlinear wave-wave interaction terms.For two selected storm events, the model generated sea-states are evaluated against available buoy data as well as against hand analyzed operational wave height charts over the northwest Atlantic. The evaluation shows that the various versions of the model can simulate the observed sea-states, reasonably well. The utility of the wave model in providing numerical guidance for offshore activities is briefly discussed.  相似文献