A flexible security system for using Internet content

The Internet and World Wide Web have introduced a powerful new way to acquire content. Previously, users had to either buy or order content on coded disks. They can now download executable code and applications directly. From the users' viewpoint, this decreases the amount of software stored on their machines. It also lets content providers customize applications by combining different vendors' content. Downloading content from the Internet brings risks: content that appears reputable may be malicious, given system access it can damage or destroy data. To contend with this risk, the author developed FlexxGuard, a flexible interpreter that dynamically derives protection domains and uses those domains to authorize content operations     

Horizontally curved isoparametric beam element with or without elastic foundation including effect of shear deformation

A new horizontally curved three-noded isoparametric beam element with or without an elastic base throughout its length, is formulated, in which the same set of parabolic shape functions in natural coordinates is used to interpolate beam geometry as well as displacements at any point of the beam. The formulation includes shear deformation effects and is also capable of accounting for torsional loading. The elastic base is assumed to offer distributed vertical reaction and torque at any point of the beam proportional to the vertical deflection and angle of twist respectively at that point. Development of the stiffness matrix is presented. A two point Gaussian quadrature rule has been followed for the necessary numerical integration. Numerical results for a few sample problems have been presented and comparison with the analytical solutions indicates the suitability of the element.     

Numerical effects in the simulation of Ginzburg–Landau models for superconductivity

Inadequate spatial mesh resolution for simulation of the time‐dependent Ginzburg–Landau equations is shown to give rise to spurious solutions. Phenomenological studies to examine the effect of the physical parameters and boundary conditions in 2D and 3D are presented to illustrate the solution structure and to highlight non‐linear effects related to evolving vortex patterns. We illustrate and explore this issue further by considering a related simplified model in which the number of vortices is equal to the ‘winding number’ that is associated with the applied boundary conditions. Using this model we demonstrate that the solution structure is non‐unique for several values of winding number. Copyright © 2004 John Wiley & Sons, Ltd.     

Efficient classification for multiclass problems using modularneural networks

The rate of convergence of net output error is very low when training feedforward neural networks for multiclass problems using the backpropagation algorithm. While backpropagation will reduce the Euclidean distance between the actual and desired output vectors, the differences between some of the components of these vectors increase in the first iteration. Furthermore, the magnitudes of subsequent weight changes in each iteration are very small, so that many iterations are required to compensate for the increased error in some components in the initial iterations. Our approach is to use a modular network architecture, reducing a K-class problem to a set of K two-class problems, with a separately trained network for each of the simpler problems. Speedups of one order of magnitude have been obtained experimentally, and in some cases convergence was possible using the modular approach but not using a nonmodular network.     

Viscosities and Sintering Rates of Composite Packings of Spheres

The effective sintering rates and viscosities of three-dimensional composite packings have been studied using a discrete numerical model. The packings consist of random mixtures of hard and soft spheres of the same size. With increasing substitution of hard particles for soft particles in the packing, the viscosity increases and the sintering rate decreases. This is particularly abrupt at well-defined rigidity thresholds where there is a transition from softlike to hardlike behavior. The site fraction of hard particles at which the transition occurs depends on the nature of the interaction between hard particles. When the contact between hard particles resists all six relative degrees of freedom (relative velocities and spins), the bonded case, the rigidity threshold coincides with the percolation threshold (site fraction ∼0.32). When the contact between hard particles resists only interpenetration, the sliding case, the threshold occurs at a site fraction of hard particles very close to unity. Results for the variation of effective properties with site fraction of hard particles are presented for these and other cases. These results can also be applied to the study of elastic percolating networks.     

Use of job aid to promote systematic search under different levels of task complexity

Job aids of various kinds have improved visual‐inspection performance. In particular, these job aids include a dynamic pointer that traces a systematic scan path across a search field. The efficacy of this specific job aid, however, has only been verified under a limited set of conditions. Moreover, the effectiveness of this job aid is a function of the speed of the pointer. Thus, it remains to be determined what pointer speeds will yield the best performances under a wide range of conditions. These conditions are defined here by four of the following task‐complexity factors: background density, fault rate, target conspicuity, and fault mix; the performance measure used is search accuracy. In general, increasing either the speed of the cursor or task complexity degraded accuracy, and the optimal pointer speed was specific to the conditions. © 2002 Wiley Periodicals, Inc.     

A constitutive model for interface friction

A new adhering-slipping rate constitutive model for interface friction is formulated. The model is fully three-dimensional in nature, but rate-independent, isothermal and isotropic in character. The conditions imposed by the requirement that the interface constitutive model be independent of an observer are carefully examined, and the new consititute model is objective or invariant under a change in observer. An incrementally objective, implicit time-integration procedure for the model is also developed. Although idealized, the model should be useful for a first-order accounting of frictional behavior at dry, unlubricated contacting interfaces in quasistatic deformation processing operations of metallic workpieces with rigid tools.     

An on-chip self-repair calculation and fusing methodology

Laser fusing is a standard technique for improving yield with memory reconfiguration and repair, but implementing fusing in production can be challenging and costly. This article introduces an electrically programmable polysilicon fuse and shows how it can reduce fuse area and programming complexity.     

Design for Testability Techniques at the Behavioral and Register-Transfer Levels

Improving testability during the early stages of the design flow can have several benefits, including significantly improved fault coverage, reduced test hardware overheads, and reduced design iteration times. This paper presents an overview of high-level design methodologies that consider testability during the early (behavior and architecture) stages of the design flow, and their testability benefits. The topics reviewed include behavioral and RTL test synthesis approaches that generate easily testable implementations targeting ATPG (full and partial scan) and BIST methodologies, and techniques to use high-level information for ATPG.