A quasi-static analysis for a class of induced-current EIT systems using discrete coils

A discrete coil EIT system is investigated for the general case of an eccentric circular inhomogeneity. The solution methodology of the forward problem of this system is explained. An optimization procedure using this forward problem solution is developed to find optimum currents that maximize the distinguishability. For an eccentric inhomogeneity problem, it is shown that the coil currents can be optimized to focus the current density in a region of interest. Optimum coil currents under limited peak coil currents constraint and limited total power constraint are obtained. Representative examples that demonstrate the performance of the system are presented.     

Communication—Processor Tradeoffs in a Limited Resources PRAM

We consider a simple restriction of the PRAM model (called PPRAM), where the input is arbitrarily partitioned between a fixed set of p processors and the shared memory is restricted to m cells. This model allows for investigation of the tradeoffs/ bottlenecks with respect to the communication bandwidth (modeled by the shared memory size m ) and the number of processors p . The model is quite simple and allows the design of optimal algorithms without losing the effect of communication bottlenecks. We have focused on the PPRAM complexity of problems that have $\tilde{O}$ (n) sequential solutions (where n is the input size), and where m ≤ p ≤ n . We show essentially tight time bounds (up to logarithmic factors) for several problems in this model such as summing, Boolean threshold, routing, integer sorting, list reversal and k -selection. We get typically two sorts of complexity behaviors for these problems: One type is $\tilde{O}$ (n/p + p/m) , which means that the time scales with the number of processors and with memory size (in appropriate ranges) but not with both. The other is $\tilde{O}$ (n/m) , which means that the running time does not scale with p and reflects a communication bottleneck (as long as m < p ). We are not aware of any problem whose complexity scales with both p and m (e.g. $O(n/\sqrt{m \cdot p})$ ). This might explain why in actual implementations one often fails to get p -scalability for p close to n .     

On the revision of probabilistic beliefs using uncertain evidence

We revisit the problem of revising probabilistic beliefs using uncertain evidence, and report results on several major issues relating to this problem: how should one specify uncertain evidence? How should one revise a probability distribution? How should one interpret informal evidential statements? Should, and do, iterated belief revisions commute? And what guarantees can be offered on the amount of belief change induced by a particular revision? Our discussion is focused on two main methods for probabilistic revision: Jeffrey's rule of probability kinematics and Pearl's method of virtual evidence, where we analyze and unify these methods from the perspective of the questions posed above.     

Virtual‐machine‐based heterogeneous checkpointing

Checkpointing an application is the act of saving the application's state during its execution on stable storage, so that if the application fails it can be restarted from the last saved state, thereby avoiding loss of the work that was already done. A heterogeneous checkpoint/restart mechanism allows one to restart an application on a possibly different hardware architecture and/or operating system than those in which the application was saved. This paper explores how to construct such a mechanism at the virtual machine level. That is, rather than dumping the entire state of the application process, the mechanism reported here dumps the state of the application as maintained by a virtual machine. During restart, the saved state is loaded into a new copy of the virtual machine, which continues running from there. The heterogeneous checkpoint/restart mechanism reported here was developed for the OCaml variant of ML. The paper reports on the main issues encountered in building such a mechanism and the design choices made, presents performance evaluations, and discusses some lessons and ideas for extending the work to native code OCaml and Java. Copyright © 2002 John Wiley & Sons, Ltd.     

Hydrodynamic effects on flow through screens at intakes

The effect of fish protective screens placed at an angle less than 90° to the flow was investigated. The effect of the approach velocity, wire area and the screen angle were considered. Mathematical equations were developed for determining the pressure drop coefficient and the angle of the flow downstream from the screen. It was found that these parameters depend primarily on the variables considered and on the drag coefficient. This finding is important for design considerations of intakes with this type of fish screen arrangement.     

The burden of injuries in the Philippines: implications for national research policy

Injuries cause 10% of the mortality and 15% of disability worldwide. However, there is a paucity of data on injuries in the developing world where two-thirds of all injury deaths occur. This is the first published report characterizing the overall problem of injuries in the Philippines, a developing country in southeast Asia. This report defines the burden of injuries in the Philippines and identifies priority areas for the national health research agenda. A systematic review of 35 years of published and unpublished data on injuries in the Philippines (1960–1995) was conducted. Injury fatality rates increased by 196% from 14.3 per 100,000 in 1960 to 42.3 per 100,000 in 1995, and one in 11 deaths in the Philippines are due to injuries. Intentional injuries account for 48% of all injury deaths and motor vehicle crashes for 15%. For 15–44 year old males, injuries account for 42% of all deaths, 67% of which are intentional. The proportion of all deaths attributable to intentional injuries has increased by 925% and that of motor vehicle crashes by 600% from 1960 to 1995. Improvements in injury surveillance and documentation of non-fatal injury outcomes are needed. Research into risk factors and potential interventions for the prevention of intentional injuries should be a priority in the Philippines.     

Reports of the DAS02 working groups

This document is a collection of four working group reports in the areas of digital libraries, document image retrieval, layout analysis, and Web document analysis. These reports were the outcome of discussions by participants at the Fifth IAPR International Workshop on Document Analysis Systems held in Princeton, NJ on 19-21 August 2002.Published online: 16 March 2004     

SIVA: A System for Coverage-Directed State Space Search

We introduce SImulation Verification with Augmentation (SIVA), a tool for coverage-directed state space search on digital hardware designs. SIVA tightly integrates simulation with symbolic techniques for efficient state space search. Specifically, the core algorithm uses a combination of ATPG and BDDs to generate directed input vectors, i.e., inputs which cover behavior not excited by simulation. We also present approaches to automatically generate lighthouses that guide the search towards hard-to-reach coverage goals. Experiments demonstrate that our approach is capable of achieving significantly greater coverage than either simulation or symbolic techniques in isolation.     

Embedded discontinuity finite element method for modeling of localized failure in heterogeneous materials with structured mesh: an alternative to extended finite element method

In this work we discuss the finite element model using the embedded discontinuity of the strain and displacement field, for dealing with a problem of localized failure in heterogeneous materials by using a structured finite element mesh. On the chosen 1D model problem we develop all the pertinent details of such a finite element approximation. We demonstrate the presented model capabilities for representing not only failure states typical of a slender structure, with crack-induced failure in an elastic structure, but also the failure state of a massive structure, with combined diffuse (process zone) and localized cracking. A robust operator split solution procedure is developed for the present model taking into account the subtle difference between the types of discontinuities, where the strain discontinuity iteration is handled within global loop for computing the nodal displacement, while the displacement discontinuity iteration is carried out within a local, element-wise computation, carried out in parallel with the Gauss-point computations of the plastic strains and hardening variables. The robust performance of the proposed solution procedure is illustrated by a couple of numerical examples. Concluding remarks are stated regarding the class of problems where embedded discontinuity finite element method (ED-FEM) can be used as a favorite choice with respect to extended FEM (X-FEM).