Passive diffusion sampling of sulfur dioxide in India: Impact assessment on arid areas     

S. Kumar  M. Mohan  R. Datta 《中国科学D辑(英文版)》2002,45(1):137-141

Environmental constraints have drastically limited options of sustainable development and have severely offset many developmental schemes. In this paper, possibilities of acidic deposition, as a counter measure of desertification, are analyzed. Seasonal data of ambient sulfur dioxide, pH of rain water and soil acidity are collected for over an year and analyzed. Arid environment of surrounding areas of Delhi is considered and analyzed. Though ambient sulfur deposition is well below critical level, it might not be truly indicative of plant survival in arid areas. Results may be useful in arid area afforestation, and polluting industries relocation, which holds tremendous potential vis-à-vis sustainable development.  相似文献   

Scattering of obliquely incident seismic waves by a cylindrical valley in a layered half-space     

S. W. Liu  S. K. Datta  M. Bouden  A. H. Shah 《地震工程与结构动力学》1991,20(9):859-870

Three-dimensional scattering of seismic waves by a cylindrical alluvial valley embedded in a layered half-space is investigated by using the combination of the boundary integral representation and the finite element method. The surface displacements due to incident plane harmonic body waves (P, SV and SH) propagating at an arbitrary angle to the axis of the cylindrical valley are evaluated numerically for two semi-elliptical alluvial valleys. The presence of the layer is found to have a strong effect on the amplification of the surface displacements in some cases. The three-dimensional motion seems to be quite critical and may cause large amplification. The surface ground motion becomes significant when compared with corresponding free-field motion as the wavelengths become comparable to the characteristic length of the valley. The maximum amplification always occurs atop the valley. Numerical results show that the amplitude and the amplification pattern of the surface displacement strongly depend upon the frequency, the angle and the type of the incident waves.  相似文献   

Transverse response of offshore pipelines to random ground motion     

T. K. Datta  E. A. Mashaly 《地震工程与结构动力学》1990,19(2):217-228

A method is presented for the determination of the transverse response of the idealized suspended span of an offshore pipeline to random seismic input. The method is based on spatial discretization of the pipe with nodal lumped masses. The earthquake is assumed to be a stationary random process characterized by a power spectral density function. The cross spectral density function between two random seismic excitations along the pipe length is defined with the help of a local earthquake power special density function, which is assumed to be the same for the two end supports of the pipeline, and a frequency dependent weighted function which decays exponentially with distance from the pipe supports. The solution is obtained in the frequency domain using the spectral approach and is presented in terms of r.m.s. displacements and stresses. The formulation adequately includes the pressure drag effect which tends to dampen the pipe motions. Utilizing this method of analysis, several idealized pipe sea bed configurations, in which the pipe is anchored between two end blocks and subjected to horizontal ground excitations normal to the pipe axis, have been analysed to predict the influence of certain important parameters on the response.  相似文献   

Response of a circular cylindrical shell to disturbances in a half-space     

Nabil El-Akily  S. K. Datta 《地震工程与结构动力学》1980,8(5):469-477

The response of a circular cylindrical shell to disturbances in an elastic half-space is the subject of this paper. Two methods of solution are presented. The first is a method of matched asymptotic expansions, and the second is a method of successive reflections.  相似文献   

Pipeline response to random ground motion by discrete model     

T. K. Datta  E. A. Mashaly 《地震工程与结构动力学》1986,14(4):559-572

The response of buried pipelines to random excitation by earthquake forces is obtained using a lumped mass model. The earthquake is considered as a stationary random process characterized by a power spectral density function (PSDF). The cross spectral density function between two random inputs along the length of the pipe is defined with the help of the local earthquake PSDF which is the same for all points, and a frequency dependent exponentially decaying (with distance) function. Soil resistance to dynamic excitation along the pipelength is obtained in an approximate manner with the help of frequency independent impedance functions derived from half-space analysis and Mindlin's static stresses within the soil due to point loads. The proposed method has the advantage that it can take into consideration the cross terms in soil stiffness and damping matrices and can consider any boundary condition that needs to be satisfied at the ends of the pipe. A parametric study is also made to show the influence of cross terms in the soil stiffness and damping matrices on the response of the pipe.  相似文献   

Torsional vibration of a twisted composite cylindrical shell of cylindrically aeolotropic materials     

Jayasri Datta 《Pure and Applied Geophysics》1971,92(1):36-44

Summary The paper is concerned with the determination of torsional vibration of a twisted composite cylindrical shell assuming the elastic constants to be proportional to the square of the distance from the axis of the shell. The solution is obtained in the form of a series in terms of Bessel functions.  相似文献   

Torsional vibration of an orthotropic Cylindrical Shell     

Jayasri Datta 《Pure and Applied Geophysics》1972,98(1):102-105

Summary This paper is concerned with the determination of torsional vibration of an orthotropic Cylindrical Shell assuming the elastic constants to be proportional to thenth power of the distance from the axis of the shell. The solution is obtained in terms of Bessel functions.c/o Dr. A. K. Dutta, P. 7. A H. B. Town, Block A, P. O. Sodepur, Dt. 24-Paraganas, West Bengal, India.  相似文献   

An instrument for seismic velocity measurements     

Satyabrata Datta 《Pure and Applied Geophysics》1965,62(1):35-40

Summary The construction and performance of an instrument for the measurement of seismic velocity in rock specimens is described. In the instrument, the transducer which receives the seismic velocity after its travel through the specimen has been excited by a method from a stable quartz crystal pulser to generate synchronised time markers at intervals of 110 millimicrosecs. The method of measurement is accurate and needs no calibration. The instrument is specially suited for the study of seismic velocity variations with pressure. The accuracy of measurement is about 1% in a 10 cm long sample in which the velocity is 6.40 km/sec.This paper is published by the kind permission of the Director General, Geological Survey of India.  相似文献   

Prediction of gas hydrate saturation throughout the seismic section in Krishna Godavari basin using multivariate linear regression and multi-layer feed forward neural network approach     

Yudhvir Singh  Rajesh R. Nair  Harmandeep Singh  Prattya Datta  Priyank Jaiswal  Pawan Dewangan  T. Ramaprasad 《Arabian Journal of Geosciences》2016,9(5):415

Stepwise linear regression, multi-layer feed forward neural (MLFN) network method was used to predict the 2D distribution of P-wave velocity, resistivity, porosity, and gas hydrate saturation throughout seismic section NGHP-01 in the Krishna-Godavari basin. Log prediction process, with uncertainties based on root mean square error properties, was implemented by way of a multi-layer feed forward neural network. The log properties were merged with seismic data by applying a non-linear transform to the seismic attributes. Gas hydrate saturation estimates show an average saturation of 41 % between common depth point (CDP) 600 and 700 and an average saturation of 35 % for CDP 300–400 and 700–800, respectively. High gas hydrate saturation corresponds to high P-wave velocity and high resistivity except in a few spots, which could be due to local variation of permeability, temperature, fractures, etc.  相似文献   

The intimate city: violence,gender and ordinary life in Delhi slums   总被引：1，自引：0，他引：1  

Ayona Datta 《Urban geography》2016,37(3):323-342

In this paper I argue for an expansion of the horizons of urban geography through a notion of the intimate city. I focus on the slum as a space where the violence of an exclusionary city is woven into its intimate material and social conditions, but where this violence is also domesticated and rendered as part of the everyday. I illustrate through three stories of intimate lives of slum women that everyday life in the slum requires the production of (1) an urban subject who shows agency not by resisting but by living with intimate violence; (2) an urban subjectivity involved in acquiring knowledge of one’s bodily terrain in order to limit this violence; and (3) an urban citizenship that argues for a “right to intimacy” as a way to claim a right to the city. This paper calls for a recasting of the public/private divide in urban geography in order to understand how violence circulates through and contravenes the boundaries of public/private, city/slum, tradition/modernity.  相似文献