nnah University

Islamabad, Pakistan

nnah University

Islamabad, Pakistan
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Gillani S.,nnah University | Shahzad F.,National University | Qayyum A.,nnah University | Mehmood R.,University of Huddersfield
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

Vehicular Ad-hoc Networks (VANETs) are the most prominent enabling network technology for Intelligent Transportation Systems. VANETs provide many new exciting applications and opportunities albeit transportation safety and facilitation applications are their core drivers. Security of vehicular networks remains the most significant concern in VANETs deployment - because it is mandatory to assure public and transportation safety. In this paper, we review the various dimensions of VANETs security including security threats, challenges in providing security in vehicular networks environment, requirements and attributes of security solutions. We also provide taxonomy and critically review of the notable security solutions - available for VANETs in literature. © 2013 Springer-Verlag.

Babar M.Z.,University of Genoa | Samar R.,nnah University | Bhatti A.I.,nnah University | Baglietto M.,University of Genoa
2015 20th International Conference on Methods and Models in Automation and Robotics, MMAR 2015 | Year: 2015

In this paper, a novel guidance scheme is presented for UAVs using the Integrated Guidance and Control (IGC) framework. The proposed guidance scheme is derived using H∞ Loop Shaping Design Procedure (LSDP). To recover from an initial cross track error, the proposed guidance algorithm produces such aileron commands that ensure the roll maneuvers without saturating the roll angle. The shaping of the open loop plant is carried out using the pre and post weights and then the robust stabilization is done by using the normalized left coprime factor uncertainty. The performance and robustness of the system are verified by introducing parametric uncertainties in to the system model. The results of the proposed scheme are verified by implementing it on a complete 6-DOF nonlinear model in the presence of wind disturbance. The simulation results indicate the effectiveness and robustness of the proposed guidance algorithm. © 2015 IEEE.

Gillani S.A.,nnah University | Shah P.A.,Petronas University of Technology | Qayyum A.,nnah University | Hasbullah H.B.,Petronas University of Technology
Advances in Intelligent Systems and Computing | Year: 2015

Vehicular ad-hoc network (VANET) is a special form of mobile ad-hoc network (MANET) in which vehicles communicate with each other by creating an ad-hoc network. Before the deployment of VANET, it is necessary to address some important issues of VANET, specially concerning about architecture, routing, mobility, and security. Medium access control (MAC) protocols specify the way in which nodes share the underlying channel. As no standard exists for VANET, the research community has previously used IEEE 802.11a and 802.11b as the MAC layer access technologies. In this paper, we have discussed that the main challenge for VANET safety applications is to design an efficient MAC, so that all safety-related messages can be sent on time and such a protocol should be reliable because human lives are involved in the case of VANET. First, the challenges and requirements of a medium access protocol for VANET are discussed and then a survey of MAC solutions available in the literature to deal with these challenges in VANET is presented. © Springer Science+Business Media Singapore 2015.

Shah P.A.,Petronas University of Technology | Shah P.A.,COMSATS Institute of Information Technology | Yousaf M.,Riphah International University | Qayyum A.,nnah University | Hasbullah H.B.,Petronas University of Technology
2012 International Conference on Computer and Information Science, ICCIS 2012 - A Conference of World Engineering, Science and Technology Congress, ESTCON 2012 - Conference Proceedings | Year: 2012

With the advancement of technology and evolution of heterogeneous access networks, mobile devices are equipped with multiple network interfaces. Usually these mobile devices use single access network for communication, hence in case of node's mobility across heterogeneous networks this single network interface based communication results in higher handover delay and service disruption time. As today's mobile devices are multi-homed, and coverage area of different access networks usually overlap, hence mobile devices may have more than one active network interfaces. These active interfaces can be used simultaneously for communication. In this paper, we have discussed the effectiveness of multi-homing and parallel transmission during and after the vertical handover process. Results show that through the use of multi-homing and parallel transmission, handover delay and service disruption time can be reduced significantly and throughput can be increased. © 2012 IEEE.

Bashir S.,Bahria University | Bashir S.,nnah University
Multimedia Tools and Applications | Year: 2015

Online opinions are one of the most important sources of information on which users base their purchasing decisions. Unfortunately, the large quantity of opinions makes it difficult for an individual to consume in a reasonable amount of time. Unlike standard information retrieval problems, the task here is to retrieve entities whose relevance is dependent upon other people’s opinions regarding the entities and how well those sentiments match the user’s own preferences. We propose novel techniques that incorporate aspect subjectivity measures into weighting the relevance of opinions of entities based on a user’s query keywords. We calculate these weights using sentiment polarity of terms found proximity close to keywords in opinion text. We have implemented our techniques, and we show that these improve the overall effectiveness of the baseline retrieval task. Our results indicate that on entities with long opinions our techniques can perform as good as state-of-the-art query expansion approaches. © 2015 Springer Science+Business Media New York

Tahir F.,Imperial College London | Ahmed Q.,Ohio State University | Bhatti A.I.,nnah University
Proceedings of the IEEE Conference on Decision and Control | Year: 2013

In this paper, we present a Switched-Decentralized Model Predictive Control (S-DMPC) scheme for the real-time flight control of a Twin Rotor System (TRS). Due to highly nonlinear dynamics and unavailability of full-state information, the linearized TRS model contains modelling (linearization) errors which cause poor state-estimation and lead to controller performance degradation. In order to address this problem, we propose an MPC-based control scheme in which, the associated (linear) observer's gain is switched according to the level of linearization error present in the model. Through experimental results, we show that the proposed S-DMPC scheme significantly improves TRS tracking in comparison to the Centralized-MPC as well as the individual (non-switched) Decentralized-MPC schemes. © 2013 IEEE.

Elahi E.,University of Sargodha | Qayyum A.,nnah University | Naz S.,nnah University
IEEE International Conference on Networks, ICON | Year: 2012

In recent years Wireless Mesh Networks (WMN) have gained lot of attention from service providers and industry due to low cost and instant deployment at both access and distribution level. The IEEE 802.11s standard addresses the need for such networks. In multi-hop networks, throughput decreases exponentially with the increase in number of hops. Thus providing QoS in multi-hop networks becomes a delicate process. The use of larger payloads can significantly enhance throughput and channel utilization. However, using larger payloads has some coupled tradeoffs. The selection of optimal payload length varies with the type of the data in the frame and flow requirements. This paper describes these tradeoffs and presents the effect of payload length on various QoS measures like throughput, jitter, packet loss ratio and end-to-end delay for different type of traffic classes and access categories. © 2012 IEEE.

Yasmin S.,nnah University | Rais R.N.B.,nnah University | Qayyum A.,nnah University
Proceedings - International Conference on Computer Communications and Networks, ICCCN | Year: 2014

In opportunistic networks, nodes hold packets in permanent storage and make independent routing decisions on sporadically emerging links. This helps to achieve connectivity even if an end-to-end contemporaneous path does not exist between a pair of nodes. Next-hop decision is generally dependent on future probability of encounters with a destination node while other constraints on nodes' resources are ignored. We argue, in this paper that considering multiple parameters related to destination dependent and independent characteristics of a node, while determining its next-hop fitness, can help achieve better performance in resource-stringent opportunistic network environments. Our proposed routing protocol, MARS, not only gets itself cognizant of mobility patterns present within the network but also combines these mobility patterns with other stochastic information about nodes' characteristics. With the help of simulations, we show that MARS is able to achieve high delivery rates and comparable end-to-end latency with well-known routing protocols while maintaining its overhead to a significantly low limit. © 2014 IEEE.

Akram M.A.,nnah University | Rizvi M.A.,nnah University | Bhatti A.I.,nnah University | Messai N.,University of Reims Champagne Ardenne
Control Engineering and Applied Informatics | Year: 2014

Identification of operating mode is a key step in the fault diagnosis of the hybrid systems. The novelty of this paper is the definition of a hybrid observer where discrete event is identified and then continuous model of a sub-system is selected for the design of observer using sliding mode technique. The observer output is finally used for mode identification and fault diagnosis. The proposed method is applied on Spark Ignition (SI) engine for misfire fault detection. The first order sliding mode observer is used to accomplish the task. The mode identification scheme is validated on data generated through hybrid model simulations as well as for data obtained from a 1.3L production vehicle.

Akram M.A.,nnah University | Bhatti A.I.,nnah University | Ahmed Q.,nnah University
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2013

Optimized fuel economy and lower pollutant emission require accurate control of air-fuel ratio in both transient and steady state region. Most of the existing AFR control schemes use oxygen sensor output as feedback, having inherent transport delays and poor performance in cold start. To overcome these problems a model based air-fuel ratio estimation scheme using HOSM is developed, to provide a feedback signal to AFR control scheme that is independent of the problems mentioned above. The methodology adopted in this paper utilizes engine speed to estimate the air-fuel ratio of the SI engine. Data is taken from a production vehicle equipped with ECU complaint to OBD-II standards. The experimental results show that the estimated signal is in good agreement with the value found in literature. The proposed scheme can be used as virtual sensor for monitoring AFR and is simple enough to be easily implemented online.

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