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International Review on
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SIDERA - A Simulation Model for Time-Triggered Distributed Real-Time Systems
by A. Hanzlik
Abstract
- SIDERA (SImulation model for DEpendable Real-time Architectures) is a
simulation model for time-triggered distributed real-time systems. It is based
on the Time-Triggered Architecture TTA and allows the simulation of large-scale
real-time systems. SIDERA provides simulation of various real-time protocol
services like system startup, communication, clock synchronization, membership
service and protocol error detection and handling. A failure simulation module
allows testing the stability of the systems under investigation in the presence
of node failures. This paper is about basic concepts of time-triggered
distributed systems and the implementation of these concepts in a simulation
environment. Further, it provides a case study of clock synchronization in
distributed systems and presents an approach that significantly improves the
synchronism in a distributed system while reducing the need for high-quality
oscillators.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Simulation, Clock Synchronization, Time-Triggered Systems, Distributed Real-Time
Computing.
Web Services and Data Integration in Distributed Automation and Information
Systems in Internet Environment
by N. Kakanakov, M. Shopov, I. Stankov, G. Spasov
Abstract
-
In this paper an abstract
model for adaptation of enterprise technologies in heterogeneous networks of
small devices is proposed. The model is based on hierarchical multi-tier
approach for better manageability and administration. Its structure allows not
only separation between business and presentation logic, but also separation of
enterprise and automation functions. Thus, changes in business and automation
logics do not affect the user. The actual distribution of functions appears on
the service and automation tiers. The level of abstraction of the model allows
its usage in various environments – home and office automation, industry,
medicine, agriculture. In the paper an experimental application of the presented
model for an effective management of HVAC (heating, ventilation and air
conditioning) systems in buildings is discussed.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
N-tier model, distributed computing, embedded systems, Industrial Ethernet, HVAC.
Grid
Middleware Technologies and OGSA: A Comparative Study
by I. Chana, S. Bawa
Abstract
- Grid Resource Management refers to the operations used to control the
capabilities provided by Grid resources and the services that are made available
to other entities. Grid enables the selection and sharing of a wide variety of
geographically distributed resources including super computers, High Performance
Computers (HPC), Massively Parallel Processors (MPPs), storage systems, data
sources, and other such resources for solving compute-intensive and
data-intensive problems. This sharing of resources is a complicated task, as it
requires the ability to bridge the differing resource management requirements of
the resource owners. Different resource owners use different middleware for
resource management as a standard middleware framework is yet to be developed.
OGSA has come up as a benchmark for this standardization. It defines principle
standards, which every grid system must adhere to, to become a future, global
grid. This paper surveys the resource models for popular Grid middleware- Globus,
UNICORE, Legion, Alchemi and SUN Grid Engine. It then compares these middleware
w.r.t. OGSA standards.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Grid middleware, Grid Computing, OGSA, Resource Management.
A Hybrid Protocol for Consistency Management of Replicas in OptorSim Simulator
by G. Belalem, Y. Slimani, B. Beldjilali
Abstract
- In large scale distributed systems, technique of replication is one of the
popular research topics and is a widely accepted way to improve the
accessibility of information and to survive the unreliability of communication
networks, but the use of this technique can be very expensive to take account
the consistency management of the replicas. In this paper, we present an
extension of the OptorSim simulator by a consistency management module of the
replicas in the Data Grids. The consistency manager inspired by the pessimistic
and optimistic approaches of consistency, this suggested approach has two
vocations, in the first time, it makes it possible to reduce the response times
compared with the completely pessimistic approach, in the second time, it gives
a good quality of service compared with the optimistic approach.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Data Grid, Replication, Optimistic approach, Pessimistic approach, Consistency,
OptorSim.
by S. Boucherkha, Z. Laboudi, M. Benmohamed
Abstract
- On-line medical image distribution is widely used nowadays between healthcare
institutions. Medical images are a type of data requiring a large processing
capacity and transmission bandwith, so, compression is often mandatory. Besides,
the integrity and confidentiality of image content is a critical issue due to
diagnostic and ethics requirements. In this work, we aim at giving an efficient
scheme to provide confidentiality for the transmission of medical images and
related data with a minimal computational effort. The proposed system consists
of an efficient combination of a lossless compression algorithm, encryption in a
CBC mode, and spatial domain watermarking to embed patient information in the
related medical image. We demonstrate experimentally that by interleaving basic
algorithms for compression, embedding and encryption in a one-pass algorithm, we
can achieve better computational performance than by using the same algorithms
in separate stages while maintaining the same security level and compression
rate.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Medical Images, Compression, Cryptography, Watermarking, Confidentiality.
Wavelet Based
Speckle Filtering of the SAR Images
by K. K. Gupta, R. Gupta
Abstract
- Synthetic Aperture Radar (SAR) images are corrupted by speckle noise due to
random interference of electromagnetic waves. The speckle degrades the quality
of the image and makes difficult to interpret, analysis and classification of
the SAR images. This paper proposes a method that reduces the speckle and
preserves the features. The features are preserved by using scale-space
correlation between the scales. The results show that the proposed method is
better than widely used filters based on the spatial domain, such as Lee, Kuan,
Frost, Ehfrost, Median, Gamma filters in terms of feature preservation. Moreover
the proposed method achieves a wide range of balances between speckle reduction
and feature preservation, and thus is applicable in different applications such
as road detection, bridge, and ribbon like structure. Further more, the proposed
method does not require prior modeling of either the image or noise statistics.
It uses the variance of the detail wavelets coefficients to estimate noise
variance.
.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Speckles, wavelet transform, multiresolution analysis.
Genetic Algorithm for Task Scheduling on Distributed Heterogeneous Computing
System
by E. Ilavarasan, P. Thambidurai
Abstract
- Distributed heterogeneous computing system are increasingly being employed for
critical applications, such as aircraft control, industrial process control, and
banking systems. Efficient application scheduling is a key issue for achieving
high performance in this system. The problem is generally addressed in terms of
task scheduling, where the tasks are the schedulable units of a program. The
task scheduling problem has been extensively studied and a large number of
scheduling heuristics have been presented in the literature. In this paper we
propose a new task-scheduling algorithm namely, Genetic Algorithm for Task
Scheduling (GATS) on heterogeneous computing system, which provides optimal
results for applications represented by directed acyclic graph. The performance
of the algorithm is illustrated by comparing the schedule length, speedup, and
efficiency with existing algorithms such as CPOP, HEFT and PSGA. The comparison
study based on randomly generated graphs and graphs of three real world
applications such as Gaussian Elimination Algorithm, Fast Fourier
Transformation, and Gauss Jordan algorithm shows that GATS algorithm
substantially outperforms existing algorithms.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Task Graph, DAG, Scheduling, Heterogeneous Computing System, Schedule length.
Logitboost of Multinomial Bayesian Classifier for Text Classification
by S. Kotsiantis, E. Athanasopoulou, P. Pintelas
Abstract
- Automated text classification has been considered as a vital method to manage
and process a vast amount of documents in digital forms that are widespread and
continuously increasing. In general, text classification plays an important role
in information extraction and summarization, text retrieval, and
question-answering. The Multinomial Bayesian Classifier has traditionally been a
focus of research in the field of text learning. This paper increases the
accuracy of Multinomial Bayesian Classifier with the usage of the Logitboost
technique. We performed a large-scale comparison on benchmark datasets with
other state-of-the-art algorithms and the proposed technique had greater
accuracy in most cases.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
text mining, learning algorithms, text representation.
Supporting
Data Changes in Multidimensional Data Warehouses
by F. Ravat, O. Teste
Abstract
- This paper is in the field of data warehouses based on “On-Line Analytical
Processing” (OLAP) technology. We detail the integration of changes in a
multidimensional schema. First, the conceptual model we provide integrates the
changes of facts (subject of analysis) and dimensions (axes of analysis). These
changes are modeled through fact and dimension versions. Second, the logical
model we provide is based on Relational-OLAP concepts. The conceptual versions
are translated into data version tables and structure tables.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Multidimensional model, Data versions, R-OLAP.
A
Rewriting Logic Based Tool for ECATNets Coverability Analysis
by N. Boudiaf, A. Chaoui
Abstract
- To analyze the behavior of Petri nets, the reachability graph allows verifying
qualitative properties. However, even for small nets, the reachability graph can
become infinite if the analyzed Petri net is unbounded. To deal with the state
space explosion problem, lazy construction methods to consider only reduced
state spaces have been elaborated. For example, the stubborn set reduced
reachability graph is usually much smaller than the complete one, but it
exhibits all dead states, if any. For unbounded nets, coverability graphs must
be used. ECATNets are a category of algebraic Petri nets based on a sound
combination of algebraic abstract types and high level Petri nets. The most
distinctive feature of ECATNets is that their semantics is defined in terms of
rewriting logic and its language Maude, allowing us to built models by formal
reasoning. In this paper, we propose a rewriting logic based tool that
implements an algorithm aiming the construction of coverability graph for
ECATNet. Some qualitative properties such as the absence of deadlock can be
checked using the constructed coverability graph. The development of this tool
is facilitated thanks to the concept of the reflectivity of rewriting logic :
the self-interpretation of this logic allows us both the modelling of an ECATNet
and acting on it. The tool is illustrated through an example.
Copyright © 2006 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Coverability Graph, ECATNets, Rewriting Logic, Maude, Dynamic Analysis,
Finite-state Systems, Infinite-state Systems.
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