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International Conference on Emerging Technologies, ICET

作者： Shujaat Hussain Muhammad Abdul Qadir Center for Distributed and Semantic Computing Mohammad Ali Jinnah University Islamabad Pakistan

Fault monitoring is one of the main activities of fault tolerant distributed systems. It is required to determine the suspected/crashed component and proactively take the recovery steps to keep the system alive. The main objective of the fault monitoring activity is to quickly and correctly identify the faults. A fault monitoring system which is quick to declare faults increases the chances of false alarms, i.e., declaration of a fault which is actually not a fault. Therefore, an ideal fault monitoring system needs to be as quick as possible in identification of faults without increasing the false alarms. Fault monitor typically detects faults by sending and receiving messages to remote objects and observing the time intervals between a message and its response. One of the major responsibilities of the monitor is to adapt these intervals according to the dynamic network and system conditions, and set them very close to the actual delays in the system. The adaptation of the delays, timeout and monitoring intervals, must not fluctuate with large amplitudes around the actual delays. Otherwise, the number of false alarms would increase or the identification of faults will be delayed. The adaptation should converge to the actual delays very fast. Adaptation of the monitoring interval in the same way as time outs adapt can not be defended. Sometimes, a distributed system (network or other components) may have abrupt change in their state for a very short duration (the transient behavior), the fault monitoring system should bypass these transients behavior, and otherwise the decisions taken on transients will have to be changed to other state very quickly which will add extra overheads both in taking the decision and then reverting it back. Our algorithm with the name of eACID (enhanced Adaptive Convergent Intelligent fault monitoring in distributed systems), when compared with the best known algorithm, ADAPTATION [Sotama et al.], yielded 16% less false timeouts and 9% mor

关键词： Detectors Remote monitoring Fault diagnosis Delay Condition monitoring distributed computing Computer crashes Fault detection Fault tolerant systems Object detection

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An efficient query matching algorithm for relational data semantic cache

An efficient query matching algorithm for relational data se...

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International Conference on Computer, Control and Communication

作者： Munir Ahmad Muhammad Abdul Qadir Muhammad Sanaullah Muhammad Farhan Bashir Centre for Distributed and Semantic Computing Mohammad Ali Jinnah University Islamabad Pakistan

ISBN: (纸本)9781424433131

Data access latency can be reduced for databases by using caching. semantic caching enhances the performance of normal caching by locally answering the partially overlapped queries. Query processing (generation of probe and remainder query from the incoming queries) and cache management need to be addressed in its totality to really enjoy these benefits. That is, there is a need of correct, complete and efficient algorithms to process incoming queries and to manage semantic and data cache. In this paper, we address this issue in the context of query processing. We have observed that the algorithm proposed by Q. Ren and his colleagues has some inefficiencies and redundancies. To overcome these inefficiencies and redundancies, we have proposed an algorithm for query matching with hierarchal stored query semantics. Proposed algorithm performs matching of stored semantics in cache with semantics of incoming query. It also has capability to generate amending query efficiently and rejects incorrect queries at initial level. Comparison of proposed algorithm is made with existing algorithm. Complexity of proposed query matching algorithm is O(n) which is smaller then the existing which have O(2n-1), n is number of attributes in a relation. Also, the proposed algorithm is capable to stop the useless processing as was done in the previous algorithms.

关键词： Query processing distributed computing Probes Information retrieval Delay distributed databases Relational databases Database systems XML

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Service optimization of in-elastic flows stripped over multiple asymmetric mobile channels

Service optimization of in-elastic flows stripped over multi...

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IEEE International Conference on Multi Topic

作者： Syed Zubair Ahmad Muhammad Abdul Qadir Muhammad Saeed Akbar Center of Distributed and Semantic Computing Mohammad Ali Jinnah University Islamabad Pakistan

In this paper, we present a stateless multi-server guaranteed rate scheduling service model that utilizes multiple, asymmetric wireless channels to maximize service guarantees for in-elastic flows. One of the major consequences of multichannel flow forwarding is the increased intra-path and inter-path end-to-end delay variations between successive packets of a stream. These variations cause problems in achieving desired service levels due to increased reorder overhead, higher packet drop-rate, and higher buffer maintenance overhead. We have aggregated the capacity of available wireless channels through a link monitoring function (LMF) and has formulated a multi-server scheduling model that ensures tight delay-bounds and lower service latency to minimize inter-path delay variations and out-of-sequence arrival. The simulation results show consistently higher performance metrics of the scheme w.r.t. end-to-end delay variations, in-order arrival, and service latency that enable reliable, scalable, guaranteed rate service during mobility.

关键词： Delay Clocks Traffic control Quality of service Maintenance Mobile computing distributed computing Processor scheduling Monitoring Measurement

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A benchmark for fault monitors in distributed systems

A benchmark for fault monitors in distributed systems

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International Conference on Emerging Technologies, ICET

作者： Shujaat Hussain Muhammad Abdul Qadir Center for Distributed and Semantic Computing Mohammad Ali Jinnah University Islamabad Pakistan

关键词： Detectors Condition monitoring Computer crashes Remote monitoring distributed computing Fault diagnosis Fault detection Delay effects Fault tolerant systems Convergence

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International Conference on Computer, Control and Communication

作者： Muhammad Fahad Muhammad Abdul Qadir Center of Distributed and Semantic Computing Mohammad Ali Jinnah University Islamabad Pakistan

ISBN: (纸本)9781424433131

One of the core tasks of mapping and merging of multiple ontologies is to produce accurate, consistent and coherent merged global ontology that promotes interoperability among heterogeneous multi-vendors semantic-based systems. Current systems for ontology mapping and merging are very restricted in terms of resolving mismatches or proposing accurate matches with no or minimum human intervention. The suggestions made by these systems do not consider all information available in the semantic knowledge of the ontologies. We developed a semantic based ontology merging system, DKP-OM that employs almost all the semantics provided in the ontologies. This paper discusses the similarity computation factors considered by DKP-OM for providing complete, consistent and coherent merged ontology. These factors find the correspondences between the concepts of ontologies and check the consistency of initial mappings found. The concept of validation during the initial stages of ontology mapping not only distinguishes our system from the existing ones' but also reduces the users' dependability for validating the consistency of the generated mappings.

关键词： Ontologies Merging Humans distributed computing Machine learning Probability Dynamic programming Runtime Process design Terminology

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Adaptive congestion control mechanism of TCP flows for performance optimization in mobile heterogeneous wireless networks

Adaptive congestion control mechanism of TCP flows for perfo...

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International Conference on Computer, Control and Communication

作者： Muhammad Saeed Akbar Syed Zubair Ahmad Muhammad Abdul Qadir Center of Distributed and Semantic Computing (CDSC) Mohammad Ali Jinnah University Islamabad Pakistan

ISBN: (纸本)9781424433131

The transmission control protocol (TCP) provides reliable transport services between end-points and enjoys predominant share as carrier of data traffic over Internet. Last mile wireless links have challenged TCP effectiveness because of fluctuations in link quality and relatively low data rates. These fluctuations cause major performance degradation in terms of reduced throughput, increased retransmission and weak fairness attributes in TCP. A TCP performance in wireless environment has been active research issue. In this paper, we propose Adaptive TCP variant which adjust congestion window adaptively and avoid congestion on network for performance optimization.. The key contribution of the proposal lies in exchanging mobility related messages between sender and receiver on the basis of lower layer triggers to handle timeout related issues in the context of mobility constraints and adjust the congestion window adaptively with respect to link characteristics. This article presents the adaptive congestion mechanism and describes the simulation results of NS 2. The result shows that Adaptive TCP provides the 10.25% to 53.75% improvement in throughput over other TCP variants in dynamically varying wireless networks conditions.

关键词： Programmable control Adaptive control Optimization Wireless networks Fluctuations Throughput Transport protocols Communication system traffic control Web and internet services Degradation

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Dependable Quality-of-Service Provisioning through Aggregate Scheduling of Multiple Service Classes on Heterogeneous Wireless Channels

Dependable Quality-of-Service Provisioning through Aggregate...

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2009 First International Conference on Future Information Networks(第一届未来信息网络国际会议)

作者： Syed Zubair Ahmad Muhammad Abdul Qadir Mohammad Saeed Akbar Center of Semantic and Distributed Computing Mohammad Ali Jinnah University Islamabad campus IslamabadPakistan

In this paper, we analyze the impact of end-to-end (E2E) delay variation on stripped sessions, whose packets are distributed over multiple links of multimode mobile terminal (MMT). The results of this analysis signify the importance of minimized out-ofsequence (OOS) arrival of packets belonging to a stream, while traversing through multiple radio networks to reach their destination. We, then propose a multi-server delay-budget ordered (MDO) scheduling scheme, that schedules back-logged packets on multiple interfaces of MMT according to their residual delay-budget metrics. In the proposed scheme, the impact of E2E delay variation on in-order packet arrival has been minimized through a link ranking function that reduces the impact of delay fluctuations. The simulation results show a consistently high performance metrics for the scheme with respect to end-to-end delay variations, packet drop rate, E2E throughput and in-order arrival which are highly desirable for interactive/live, and buffered video streams running on MMT devices in uplink or/and downlink paths.

关键词： component multi-server delay-budget ordered scheduling Quality-of-service(QoS) out-of-sequence(OOS) packet arrival capacity aggregation one-way trip time estimation

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Cross attribute knowledge: A missing concept in semantic cache query processing

Cross attribute knowledge: A missing concept in semantic cac...

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IEEE International Conference on Multi Topic

作者： Muhammad Azeem Abbas Muhammad Abdul Qadir Centre for Distributed and Semantic Computing Faculty of Engineering and Sciences Mohammad Ali Jinnah University Islamabad Pakistan

Any semantic cache query processing technique is said to be efficient, if it is able to find maximum possible or complete answer from the cache within tractable time. This work evaluates previous semantic cache query processing techniques on the basis of maximum data retrieval (MDR). For this several cases are provided where previous query processing techniques are unable to find maximum possible or complete answer even when it is present in the cache. It is due to neglecting implicit knowledge (cross attribute knowledge) present in semantics of the cache. This knowledge is identified and formally presented here in this work.

关键词： Query processing Information retrieval distributed computing Knowledge engineering Memory Telecommunication traffic Delay Indexing Region 3 Probes

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QoS optimization of in-elastic flows stripped over multiple asymmetric channels in mobile networks

QoS optimization of in-elastic flows stripped over multiple ...

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International Conference on Ultra Modern Telecommunications and Workshops (ICUMT)

作者： Syed Zubair Ahmad Muhammad Abdul Qadir Mohammad Saeed Akbar Center of Semantic and Distributed Computing Mohammad Ali Jinnah University Islamabad Pakistan Faculty of Agriculture University of Agriculture Faisalabad Pakistan

In this paper, we analyze the impact of end-to-end (E2E) delay variation on stripped sessions, whose packets are distributed over multiple links of multi-mode mobile terminal (MMT). The results of this analysis signify the importance of minimized out-of-sequence (OOS) arrival of packets belonging to a stream, while traversing through multiple radio networks to reach their destination. We, then propose a multi-server delay-budget ordered (MDO) scheduling scheme, that schedules backlogged packets on multiple interfaces of MMT according to their residual delay-budget metrics. In the proposed scheme, the impact of E2E delay variation on in-order packet arrival has been minimized through a link ranking function that reduces the impact of delay fluctuations. The simulation results show a consistently high performance metrics for the scheme with respect to end-to-end delay variations, packet drop rate, E2E throughput and in-order arrival which are highly desirable for interactive/live, and buffered video streams running on MMT devices in uplink or/and downlink paths.

关键词： Mobile computing Delay estimation Downlink Delay effects Processor scheduling Agriculture Transport protocols Bandwidth distributed computing Radio network

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S-point A semantic based E-learning content development tool

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Journal of Applied Sciences 2008年第1期8卷 127-133页

作者： Ihsan, Imran Rehman, Mohib Ur Ahmed, Mobin Uddin Qadir, M. Abdul Center for Distributed and Semantic Computing Mohammad Ali Jinnah University Jinnah Avenue Blue area Islamabad Pakistan

Microsoft® PowerPoint is the most popular e-learning content development tool. The effectiveness and easy to use of PowerPoint together with third party tools seems to make the idea to develop-e-learning with PowerPoint work but PowerPoint carmot be considered as a premier e-learning tool. The reason might be the drawbacks of PowerPoint in terms of its file size, inter-operability and openness. This research describes architecture of a new e-learning content development tool that not only has the look and feel of PowerPoint but also overcomes the drawbacks of PowerPoint. We call! this tool as S-Point-A semantic Based eLearning Content Development tool that is based on the Open Reusability Benchmark. With help of this tool teachers can develop learning objects that are more semantically meaningful and semantically searchable. © 2008 Asian Network for Scientific Information.

关键词： Reusability

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