Dynamic Plasticity in Pile-Soil Interaction Problems

The dynamic soil-pile interaction problem is solved by the method of characteristics. The nonlinear, non-homogeneous problem was idealized as a piecewise linear problem. The numerical instability of semi-infinite soil column model has been reported, and a stable model, wherein the soil column below, the pile tip is replaced by a single spring and dashpot, has also been presented. The results obtained from the method of characteristics have been compared with those obtained by explicit finite difference scheme. The convergence and stability were studied numerically

Spanning trees short or small

We study the problem of finding small trees. Classical network design problems are considered with the additional constraint that only a specified number $k$ of nodes are required to be connected in the solution. A prototypical example is the $k$MST problem in which we require a tree of minimum weight spanning at least $k$ nodes in an edge-weighted graph. We show that the $k$MST problem is NP-hard even for points in the Euclidean plane. We provide approximation algorithms with performance ratio $2\sqrt{k}$ for the general edge-weighted case and $O(k^{1/4})$ for the case of points in the plane. Polynomial-time exact solutions are also presented for the class of decomposable graphs which includes trees, series-parallel graphs, and bounded bandwidth graphs, and for points on the boundary of a convex region in the Euclidean plane. We also investigate the problem of finding short trees, and more generally, that of finding networks with minimum diameter. A simple technique is used to provide a polynomial-time solution for finding $k$-trees of minimum diameter. We identify easy and hard problems arising in finding short networks using a framework due to T. C. Hu.Comment: 27 page

Reductive Biotransformation of Ethyl Acetoacetate: A Comparative Studies using Free and Immobilized Whole Yeast Cells

Bioreduction of ethyl acetoacetate with free and immobilized yeast whole cell was achieved by using water and sucrose combination. After detachment from immobilized beads under basic condition, the corresponding ethyl(S)-(+)-3-hydroxybutanoate was isolated with 98 to 100% yield. Immobilized beads of yeast whole cell were prepared at different temperature which affects the morphology and physiology of the beads for the diffusion of the enzyme, which shown the maximum conversion of the substrate to products as compared to the free yeast whole cell

Case Histories of Foundations With Stone Columns

The paper presents case histories of performance of foundations where stone columns were provided, along with relevant data regarding structural systems, soil conditions, construction methods and field control criteria. A wide range of applications are included comprising stone columns for area treatment and stone column in small and large groups for isolated footings, pipe pedestals and bridge abutments. In some of the cases design load exceeded the estimated yield load over a part of the stone column length yet collapse did not occur because the soil stress around the stone column increased as more load was passed on to the soil when yield stress was exceeded. There was also the benefit of drainage afforded by the stone columns. Load test data are furnished to substantiate the design approach which takes into consideration the strengthening of the soil annulus around the stone column resulting from compaction and subsequent consolidation

A Firm Level Framework for Electronic Commerce: An Information Systems Perspective

Many firms do not have their business plans and information systems plans in place for embarking on electronic commerce. A firm level framework for electronic commerce will help firms to plan and align their ECIS (Electronic Commerce Information Systems) to business and information systems strategies. This paper develops such a framework. The four components of the framework are information architecture, business processes, choice of technology applications, and customer focus. A brief discussion on the significance of these components to electronic commerce is include

Ground Versus Soil: A New Paradigm in Geotechnical Engineering Education

me of the practitioners of geotechnical engineering tend to confuse Ground with Soil. It is not just semantics but the terms have d eeper technical and philosophical implications. Soi l is a material which can be handled, felt, seen, sme lt, tasted, and tested in small to medium size samples while ‘Ground’ is an entity that exists in- situ. Just as the adage, ‘The total is more than th e sum of the individual parts’, predicting the behavi or of ground from the so-called properties measured on samples collected from the field is muc h more complex and involves judgment. Ground is an intricate natural entity very similar to ‘Humans’ and exhibits behavioral responses rather than merely possess properties like other en gineering materials. Humans have organs and traits such as being jovial, sad, friendly, angry, misanthropic, etc. but do not have properties. Thei r behavioral responses depend on genetics, environmen t in which they grow, personality they develop and to impetus they experience. Similarly, the genetics of ground is defined by its formation (alluvial, marine, residual, colluvial, a eolin, etc.) depending upon how physiogamy forms the deposit. Ground, one tends to believe, is a sol id mass on which structures are built, becomes suddenly a fluid under specific aggravating circums tances such as consisting loose saturated sand with small amount of fines but subjected to seismic activity of medium to high intensity. On the other hand, a river in flood can erode the ground b y removing particles by its high velocity leading to scour. Slopes on which civilizations thrive, bec ome unstable and sometimes even catastrophic under heavy rainfall, coupled with human activities of deforestation, cutting/steepening of slopes, saturating it by ignorance or callousness, etc. The paper presents a new paradigm that emphasizes the need to visualize Ground, not just as a materia l but rather an entity, and view Geotechnical Engineering comprehensively, beyond a mechanistic s tandpoint

INDEMICS: An Interactive High-Performance Computing Framework for Data Intensive Epidemic Modeling

We describe the design and prototype implementation of Indemics (_Interactive; Epi_demic; _Simulation;)—a modeling environment utilizing high-performance computing technologies for supporting complex epidemic simulations. Indemics can support policy analysts and epidemiologists interested in planning and control of pandemics. Indemics goes beyond traditional epidemic simulations by providing a simple and powerful way to represent and analyze policy-based as well as individual-based adaptive interventions. Users can also stop the simulation at any point, assess the state of the simulated system, and add additional interventions. Indemics is available to end-users via a web-based interface. Detailed performance analysis shows that Indemics greatly enhances the capability and productivity of simulating complex intervention strategies with a marginal decrease in performance. We also demonstrate how Indemics was applied in some real case studies where complex interventions were implemented

Settlement Analysis of Circular Footings on Layered Soil Systems

Many studies are available on the settlement analysis of footings on a homogeneous soil deposit underlain by a rigid base. However, the soil profile is seldom homogenous and typically a layered soil system is encountered in practice. The present study deals with the settlement profiles of soil underneath a circular footing of radius equal to a, and resting on a finite two-layered soil system with thicknesses equal to H1 and H2. The deformation moduli and Poisson’s ratios of the two layers are E1, υ1, and E2, υ2. The settlement profiles are proposed for varying H1/a and H2/a ratios (H1/a= 0.2, 0.5, 1, 2, 4 and 6, and H2/a= 1, 2, 4 and 6). The moduli ratio E1/E2is varied as 0.01, 0.05, 0.1, 0.5, 1, 2, 5 and 20. The extent of settlement due to load is also proposed from the surface settlement profile which can help in determining the influence of a footing on the neighboring footing or structure. The analysis is carried out using PLAXIS 2D vAE. In addition, the settlement influence factors are proposed for the above mentioned ratios to estimate the maximum settlement of the footing on a layered system. The results are also compared with the settlement measured in a building on a layered system in Adelaide, Southern Australia, and the results are found to be comparable

Bicriteria Network Design Problems

We study a general class of bicriteria network design problems. A generic problem in this class is as follows: Given an undirected graph and two minimization objectives (under different cost functions), with a budget specified on the first, find a <subgraph \from a given subgraph-class that minimizes the second objective subject to the budget on the first. We consider three different criteria - the total edge cost, the diameter and the maximum degree of the network. Here, we present the first polynomial-time approximation algorithms for a large class of bicriteria network design problems for the above mentioned criteria. The following general types of results are presented. First, we develop a framework for bicriteria problems and their approximations. Second, when the two criteria are the same %(note that the cost functions continue to be different) we present a ``black box'' parametric search technique. This black box takes in as input an (approximation) algorithm for the unicriterion situation and generates an approximation algorithm for the bicriteria case with only a constant factor loss in the performance guarantee. Third, when the two criteria are the diameter and the total edge costs we use a cluster-based approach to devise a approximation algorithms --- the solutions output violate both the criteria by a logarithmic factor. Finally, for the class of treewidth-bounded graphs, we provide pseudopolynomial-time algorithms for a number of bicriteria problems using dynamic programming. We show how these pseudopolynomial-time algorithms can be converted to fully polynomial-time approximation schemes using a scaling technique.Comment: 24 pages 1 figur