Abstract

We consider the problem of reliable message transmission between two synchronous players connected by n wires, some t< n 2 of which may be faulty. We show how to get reliability “for free”—reliable transmission of b bits involves a total communication of only O (b) bits, when b is large enough. We also construct an efficient Perfectly Secure Message Transmission Protocol.

Abstract

We provide a complete characterization of directed networks in which probabilistic reliable communication is possible. We also outline a round optimal protocol for the same.

Abstract

We consider perfect verifiable secret sharing (VSS) in a synchronous network of n processors (players) where a designated player called the dealer wishes to distribute a secret s among the players in a way that no t of them obtain any information, but any t + 1 players obtain full information about the secret. The round complexity of a VSS protocol is defined as the number of rounds performed in the sharing phase. Gennaro, Ishai, Kushilevitz and Rabin showed that three rounds are necessary and sufficient when n > 3t. Sufficiency, however, was only demonstrated by means of an inefficient (i.e., exponential-time) protocol, and the construction of an efficient three-round protocol was left as an open problem. In this paper, we present an efficient three-round protocol for VSS. The solution is based on a three-round solution of so-called weak verifiable secret sharing (WSS), for which we also prove that three rounds is a lower bound. Furthermore, we also demonstrate that one round is sufficient for WSS when n > 4t, and that VSS can be achieved in 1 + ε amortized rounds (for any ε > 0 ) when n>3t.

Abstract

When an active bedrock fault ruptures, the movement along the fault propagates through the overlying soil and produces zones of intense shear. If the fault movement propagates upto or near the ground surface, the damage to constructed facilities due to faulting, in conjunction with that induced by strong ground motion, can be significant. This paper contributes to the understanding of the response of soil deposits to the underlying bedrock fault displacement. In the conventional attenuation relationship, peak ground acceleration shows maximum value at the closest distance from the fault. However, in the real observations, sometimes it is found that the damage near to the surface fault is not maximum, instead it is high little away from the surface rupture zone. To understand the above-mentioned response of soil deposits, we attempted to develop a new application to Applied Element Method (AEM) by modeling the fault rupture zone. In this, we study the behavior of dip-slip faults. The effect of the slip velocity on the ground motion is studied first and then the attenuation of PGA in the near fault zone is studied. Effect of the material properties is also discussed.

Abstract

This article aims to understandthe response of soil deposits underlying bedrock fault displacement in three dimensions. When an active bedrock fault ruptures movement along the fault propagates through the overlying soil and produces zones of intense shear. Hence it is important to study the sruface behaviour based on fault characteristics. Hence we attempted to develop application of applied element method by modelling the fault rupure zone. In this article we have modelled the fault rupture problem in three dimensions. First a simple model is used to illustrate absorption of the bedrock deformation by the overlying soin in elastic case. In the later part nonlinear analysis is carried out to study the complex failure propogation in three dimensions. Influence of mechanical propertices of the material is also discussed.

Abstract

The earthquake-resistant design methodology in most existing codes of practice is based on ensuring no collapse” during the most severe event expected at the given site while most of the input energy is dissipated through inelastic deformations. Evolution of the performance-based design over the last decade has seen a few performance levels added up to this so that the structure remains functional even after a moderately strong event. This methodology however overlooks the possibility that in case of multiple earthquake events expected during the design life of the structure the structure may get gradually damaged and that it may not be feasible to carry out repairs in the structure after every damaging event. As a result, the structure may collapse earlier than expected and perhaps during an event of moderate intensity. To address such a concern a new spectrum, called as design force ratio spectrum is proposed in this paper. DFR spectrum gives the ratio by which the design yield force level of a conventionally-designed single degree of freedom structure should be raised such that the damage caused by all earthquake events expected to occur during its lifetime is limited to a specified level. A numerical study is carried out for a hypothetical seismic region by following a simple procedure based on several assumptions and DFR spectra are obtained for elastic-perfectly plastic oscillators when the return periods of earthquakes follow exponential distribution over the entire range of magnitudes.

Abstract

It is very well recognized that structure which is stiff interacts dynamically with soil during earthquakes. In order to carry out the investigation in dynamic way, the main problem that will arise in modeling is unbounded nature of soil medium. The real field is not surrounded by any boundary and any numerical model that we study have to be defined by using a proper boundary that takes care of radiation of dynamic energy into unbounded soil. Conventional boundaries used for studying the structural analysis may not give proper results for qualitative discussion. So, we need to model the soil similar to actual field conditions. For that we need to model an absorbing boundary condition.

Abstract

On 26 December 2004 a devastating earthquake of magnitude 9.3 occurred in Sumatra region of Indonesia. This earthquake produced the world’s deadliest tsunami in the Indian Ocean region that claimed more than 300, 000 lives. This earthquake was quickly followed by another great one of magnitude 8.7 on 28 March 2005 in the same region. This is for the first time in the known history of Seismology that 2 great earthquakes have occurred in close spatial proximity in such a quick succession.

Abstract

The great devastating tsunamigenic earthquake of 26 December 2004 in sumatra was quickly followed by another great one on 28 march 2005 in the same region. This is for the first time in the known histroy of seismology that 2 great earthquakes have occurred in close spatial proximity in such a quick succession. In the present study we highlight the role of the multiple plate junction comprising the India, Burma, Australia and Sunda plates in in generation of such great earthquakes.

Abstract

This article aims to understand the response of soil deposits underlying bedrock fault displacement in three dimensions. When an active bedrock fault ruptures, movement along the fault propagates through the overlying soil and produces zones of intense shear. Hence, it is important to study the surface behaviour based on fault characteristics. Hence we attempted to develop application of Ap- plied Element Method by modelling the fault rupture zone. In this article, we have modelled the fault rupture problem in three dimensions. First, a simple model is used to illustrate absorption of the bedrock deformation by the overlying soil in elastic case. In the later part, nonlinear analysis is car- ried out to study the complex failure propagation in three dimensions. Influence of mechanical properties of the material is also discussed.