			Home About us Contact

Implementation Aspects (implementation + aspect)

Distribution by Scientific Domains

Engineering	62%

Selected Abstracts

Multivariate Bayesian regression applied to the problem of network security

JOURNAL OF FORECASTING, Issue 8 2002
Kostas Triantafyllopoulos
Abstract An Erratum has been published for this article in Journal of Forecasting 23(6): 461 (2004). This paper examines the problem of intrusion in computer systems that causes major breaches or allows unauthorized information manipulation. A new intrusion-detection system using Bayesian multivariate regression is proposed to predict such unauthorized invasions before they occur and to take further action. We develop and use a multivariate dynamic linear model based on a unique approach leaving the unknown observational variance matrix distribution unspecified. The result is simultaneous forecasting free of the Wishart limitations that is proved faster and more reliable. Our proposed system uses software agent technology. The distributed software agent environment places an agent in each of the computer system workstations. The agent environment creates a user profile for each user. Every user has his or her profile monitored by the agent system and according to our statistical model prediction is possible. Implementation aspects are discussed using real data and an assessment of the model is provided. Copyright © 2002 John Wiley & Sons, Ltd. [source]

A numerical approximation of the thermal coupling of fluids and solids

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2009
Javier Principe
Abstract In this article we analyze the problem of the thermal coupling of fluids and solids through a common interface. We state the global thermal problem in the whole domain, including the fluid part and the solid part. This global thermal problem presents discontinuous physical properties that depend on the solution of auxiliary problems on each part of the domain (a fluid flow problem and a solid state problem). We present a domain decomposition strategy to iteratively solve problems posed in both subdomains and discuss some implementation aspects of the algorithm. This domain decomposition framework is also used to revisit the use of wall function approaches used in this context. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Pressure segregation methods based on a discrete pressure Poisson equation.

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2008
An algebraic approach
Abstract In this paper, we introduce some pressure segregation methods obtained from a non-standard version of the discrete monolithic system, where the continuity equation has been replaced by a pressure Poisson equation obtained at the discrete level. In these methods it is the velocity instead of the pressure the extrapolated unknown. Moreover, predictor,corrector schemes are suggested, again motivated by the new monolithic system. Key implementation aspects are discussed, and a complete stability analysis is performed. We end with a set of numerical examples in order to compare these methods with classical pressure-correction schemes. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Implementation of a stabilized finite element formulation for the incompressible Navier,Stokes equations based on a pressure gradient projection

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2001
Ramon Codina
Abstract We discuss in this paper some implementation aspects of a finite element formulation for the incompressible Navier,Stokes equations which allows the use of equal order velocity,pressure interpolations. The method consists in introducing the projection of the pressure gradient and adding the difference between the pressure Laplacian and the divergence of this new field to the incompressibility equation, both multiplied by suitable algorithmic parameters. The main purpose of this paper is to discuss how to deal with the new variable in the implementation of the algorithm. Obviously, it could be treated as one extra unknown, either explicitly or as a condensed variable. However, we take for granted that the only way for the algorithm to be efficient is to uncouple it from the velocity,pressure calculation in one way or another. Here we discuss some iterative schemes to perform this uncoupling of the pressure gradient projection (PGP) from the calculation of the velocity and the pressure, both for the stationary and the transient Navier,Stokes equations. In the first case, the strategies analyzed refer to the interaction of the linearization loop and the iterative segregation of the PGP, whereas in the second the main dilemma concerns the explicit or implicit treatment of the PGP. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Circuits, computers, and beyond Boolean logic,

INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 5-6 2007
Tamás Roska
Abstract Historically, the invention of the stored programmable computer architecture, introduced by John Von Neumann, was also influenced by electrical circuit implementation aspects, as well as tied to fundamental insight of logic reasoning. It can also be considered as a mind-inspired machine. Since then, the implementation of logic gates, control and memories has developed independently of the architecture. The Cellular Wave Computer architecture (IEEE Trans. Circuits Syst. II 1993; 40:163,173; Electron. Lett. 2007; 43:427,449; J. Circuits Syst. Comput. 2003; 5(2):539,562) as a spatial,temporal universal machine on flows has also been influenced by circuit aspects of very large-scale integration (VLSI) technology, as well as some motivating living neural circuits, via the cellular nonlinear (neural) network (CNN). It might be considered as a brain-inspired machine. In this paper, after summarizing the main properties of the Cellular Wave Computer, we highlight a few basic properties of this new kind of computer and computing. In particular, phenomena related to (i) the one-pass solution of a set of implicit equations due to real-time spatial array feedback, (ii) the true random signal array generation via the insertion of the continuous physical noise signals, (iii) the finite synchrony radius due to the functional delay of wires, as well as to (iv) biology relevance. We also show that the Cellular Wave Computer is performing spatial,temporal inference that goes beyond Boolean logic, a characteristic of living neural circuits. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Modularizing inference in large causal probabilistic networks

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 2 2003
Kristian G. Olesen
This article describes a number of implementation aspects of modular inference in large medical expert systems based on causal probabilistic networks. Examples are provided from the neuromuscular diagnosting system the muscle and nerve inference network (MUNIN). The inference procedure is outlined and the principal data structure underlying the inference procedure are described. A condensed summary of selected technical details of the inference procedure in causal probabilistic networks (CPNs) is provided. This is required for understanding the implemented modularization of the inference. The modularization of the inference implies a need for transfer of information between modules, which is realized by establishing communication channels between modules. Modules are also used to perform inference by conditioning, a method that reduces storage requirements to a manageable size and thereby prepares the way for MUNINs migration to common PCs. © 2003 Wiley Periodicals, Inc. [source]

Implementing belief function computations

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 1 2003
Rolf Haenni
This article discusses several implementation aspects for Dempster-Shafer belief functions. The main objective is to propose an appropriate representation of mass functions and efficient data structures and algorithms for the two basic operations of combination and marginalization. © 2003 Wiley Periodicals, Inc. [source]

A Unified Dynamic Model Formulation for Robotic Manipulator Systems

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2003
Anjan Kumar Swain
This paper addresses the problem of the formulation of a unified dynamic model for sundry robotic manipulator systems derived from the first principle of mechanics instead of the existing formulation based on linear separability principle. It provides a systematic derivation, evaluation, and subsequent conceptual interpretation of manipulator dynamics model. Further, it analyzes the generality of the unified model over a wide range of manipulator configurations. In addition, it describes the implementation aspects of the unified model. © 2003 Wiley Periodicals, Inc. [source]