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International Review on Computers and Software - September 2006 - Papers

Automatic Feature Extraction to COSMOS-7 Content Models
A Fuzzy Algorithm for Real-Time Scheduling of Soft Periodic Tasks
An Integrated Metrics Based Approach for Usability Engineering
Network Priority Mapping Using Dynamic RT-CORBA Scheduling Service
Ontology-Driven Semantic Interoperability
Multicast Retransmission Strategies for Content Delivery in Heterogeneous Mobile Internet Environments
Stability and Performance Analysis of Clock Synchronization in FlexRay
Tolerating DDoS Attacks Using Dynamic Rate Limiting
Fully Distributed Security Architecture for MANET
Recognition of Bilingual segmented characters (Gurmukhi and Roman)

International Review on Computers and Software - Papers

Automatic Feature Extraction to COSMOS-7 Content Models
by M. J. Parmar, M. C. Angelides

Abstract - Extracting and modeling multimedia content in MPEG-7 is a laborious task as most systems use manual or partially automatic extraction methods. Systems that use partially automatic extraction techniques tend to use a limited set of features that are of little or no use to other applications negating the purpose of the MPEG-7 standard. In this paper we present our automatic extraction methods for the structural components of media. In particular, we extract from scenes, shots, objects and spatial and temporal relationships. These features are then processed and incorporated into an MPEG-7 content model that is rich enough to facilitate content filtering.

Keywords: Multimedia content modeling, feature extraction, MPEG-7.

A Fuzzy Algorithm for Real-Time Scheduling of Soft Periodic Tasks

by M. Sabeghi, M. Naghibzadeh

Abstract - Many scheduling algorithms have been studied to guarantee the time constraints of real-time processes. Scheduling decision of these algorithms is usually based on parameters which are assumed to be crisp. However, in many circumstances the values of these parameters are vague. The vagueness of parameters suggests that we make use of fuzzy logic to decide in what order the requests should be executed to better utilize the system and as a result reduce the chance of a request being missed. We have proposed a new fuzzy algorithm called highest fuzzy priority first. The performance of this algorithm is compared with the well-known earliest deadline first (EDF) algorithm as well as least laxity first (LLF) algorithm through simulation. The simulations were divided into two parts. Firs, the tasks were considered to be preemptable, and second tasks were assumed to be non-preemptable. Simulation results show that this fuzzy approach outperforms the EDF and LLF. It is concluded that the proposed fuzzy approach is very promising and it has the potential to be considered for future research.

Keywords: Fuzzy real time scheduling, EDF, LLF, MFDF, MFLF.

An Integrated Metrics Based Approach for Usability Engineering
by H. S. Jabbar, T. V. Gopal

Abstract - Usability Assessment (UA) is a method that is used to elicit the quality of software products through regular tests with potential users by a variety of methods and models. However, existing methods either falls in qualitative methods, which generally estimate users opinion of a software product which called (subjective assessment) or falls in quantitative methods, which focus on the performance measurement of the software product which is called (objective assessment). In this paper, we have proposed an Integrated Metrics Based Approach For Usability Engineering (IMAUE), which combine both qualitative and quantitative factors to complement the analysis process. Qualitatively, we have contributed to the factors of (1) conducting UA with fewer requirements by means of time, budget and resources (2) establish 2-way interaction between the user and the tester by interviewing users responses in the UA (3) employing dynamic tasks to fill the gap of communication and convert the UA into a discovery process. Quantitatively, we have proposed various models and metrics that can be used to measure the level of usability, those metrics are (1) interviewing time (2) number of errors (3) task accomplishment (4) time for the task and (5) users satisfaction. In order to clarify the assumptions of the proposed model, we have validated our model against two experimental case studies.

Keywords: UA, literature overview, research needs, IMAUE, case studies.

Network Priority Mapping Using Dynamic RT-CORBA Scheduling Service
by T. Guesmi, S. Hasnaoui, H. Rezig

Abstract - Distributed computer control in complex embedded systems and their software components gain complexity when these systems are equipped with many microcontrollers which oversee diverse electronic control units connecting hundreds or thousands of analog and digital sensors and actuators. These systems need new inter-object communication patterns thus QoS-enabled middleware services and mechanisms have begun to emerge. It is also, widely known that Control Area Networks (CAN) are used in real-time, distributed and parallel processing which cover manufacture plants, humanoid robots, networking fields. We show how prioritization of messages over the physical CAN network can be achieved, when adopting the use of RT-CORBA distributed scheduling service which implements a dynamic scheduling policy to achieve end-to-end predictability and performance.

Keywords: Real-Time Scheduling, Earliest Deadline First, CAN Bus, Intermediate Deadline, Network Priority Mapping.

Ontology-Driven Semantic Interoperability

by L. V. Stoimenov, E. O. Kajan, S. Djordjevic-Kajan

Abstract - Semantic interoperability between applications, systems, organizations, and communities appears today as a crucial feature that should allow their intelligent communications with a minimum or completely without human interventions. In this paper we introduce our common concept for a semantic interoperable middleware kernel that may satisfy the requirements of many different applications. Finally, a short overview of implementation for two different domains (GIS and B2B) has given.

Keywords: Interoperability, semantics, ontologies, framework.

Multicast Retransmission Strategies for Content Delivery in Heterogeneous Mobile Internet Environments

by N. Reyes, J. Mahnke, I. Miloucheva, K. Jonas

Abstract - For efficient deployment of new reliable multicast applications in heterogeneous mobile Internet environments, appropriate retransmission strategies are proposed.
The focus is the minimization of the protocol overhead for reliable transport taking into account behavior in mobile networks (f.i. loss and handover behavior) and application requirements (such as carousel file transfer, one-to-many download and media streaming combined with recording).
The proposed techniques are designed as building blocks for localized multicast error control supported by access routers. Considering IETF RMT standardization work, the discussed retransmission approaches can be used for flexible configuration of tree-based reliable multicast protocols in converged wired and wireless Internet environment.
The implementation is based on Linux IPv6 environment. Simulations in ns2 focusing on the benefits of the proposed multicast retransmission schemes for particular application scenarios are presented
.

Keywords: reliable multicast, retransmission, carousel, one-to-many download, error control, network simulation.

Stability and Performance Analysis of Clock Synchronization in FlexRay

by A. Hanzlik

Abstract - This paper presents a case study on the performance of a distributed clock synchronization algorithm used in FlexRay, a communication protocol designed to meet the requirements of dependable, fault-tolerant real-time applications. The FlexRay industry consortium drives forward the standardization of a fault-tolerant communication system for advanced automotive applications. In this case study we will analyze two different configurations for typical automotive applications by means of simulation. The focus of the simulation experiments is the assessment of performance and stability of the FlexRay clock synchronization algorithm in the presence of varying clock drift rates. For the analysis we will use SIDERA, a simulation model for time-triggered distributed systems.

Keywords: Clock Synchronization, Global Time, Time-Triggered Systems, Clock drift, Real-Time Communication Protocol.

Tolerating DDoS Attacks Using Dynamic Rate Limiting

by K. Kumar, R. C. Joshi, K. Singh

Abstract - Distributed Denial of Service (DDoS) attacks pose a serious threat to availability of Internet Services. Several schemes have been proposed for countering DDoS attacks directed at an Internet Server, but they suffer from a range of problems, some of them being impractical and others not being effective against these attacks. We propose a dynamic rate throttling technique that will greatly minimize the impact of attack. The basic mechanism is to have monitoring, rate limiting and filtering at edges of ISPs. The participating routers, start there function after getting a signal from a server under attack. Our scheme is invoked only during attack times, and is able to mitigate attack traffic through dynamic filtering. Server instructs edge routers to rate limit the traffic according to the share of traffic which is being passed through particular edge router. The solution proposed is an ISP level solution which is practical enough to be implemented. We simulate the scheme in NS-2 in Linux System. We use an Internet type topology to test our scheme. Web and FTP traffic was generated to evaluate the effectiveness of scheme. Our scheme shows good improvement over static router throttling techniques which were proposed earlier. Hence we believe that the scheme proposed in this paper is a promising approach to stop DDoS attacks.

Keywords: Congestion control, Distributed Denial of service, Network level security and protection, router throttling.

Fully Distributed Security Architecture for MANET
by A. Shajin Nargunam, M. P. Sebastian

Abstract - Secured communication in mobile ad hoc network is a crucial issue due to dynamic nature of the network topology. Due to lack of centralized control, issuing certificates from a centralized certification agent is not possible in ad hoc network. The major problem in providing security services in such infrastructure less networks is how to manage the cryptographic keys that are needed In MANET any node may compromise the packet routing functionality by disrupting the route discovery process.. These unique characteristics of mobile ad hoc networks causes a number of nontrivial challenges to security design such as open network architecture, shared wireless medium, stringent resource constraints and highly dynamic topology. These challenges make a cause for building multi-fence security solution that achieves both extensive protection and desirable network performance. We propose a novel cluster based security scheme to protect mobile ad hoc network link layer and network layer operations of delivering packet over the multihop wireless channel. The dynamic network topology can be managed efficiently by the proposed cluster based architecture. A well-behaving node becomes a cluster member after the initial trust verification process. The membership validity period of a node depends on how long it has stayed and behaved well. Non overlapping clusters are created using the dynamic cluster creation algorithm. The cluster construction is fully distributed so efficiency is not degraded by node mobility.

Keywords: Cluster, Denial of Service and MANET Security.

Recognition of Bilingual Segmented Characters (Gurmukhi and Roman)
by R. Dhir, C. Singh

Abstract - Recognition of bilingual script in an image of a document page is of primary importance for a system processing bilingual document. In this paper two essential sub stages of recognition phase, feature extraction and classification has been discussed for segmented Gurmukhi and Roman characters. Two classifier schemes have been proposed for recognition of machine printed Bilingual characters. It has been found that structural and statistical features provide very good results. With both the classifiers a good accuracy is achieved for segmented Gurmukhi and Roman characters without preprocessing.

Keywords: Bilingual Script, Neuro Fuzzy, nearest neighbor, segmentation, simplified fuzzy.