Faculty of Engineering, Applied Science and Technology

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Numerical analysis of stimulated Raman scattering in nonlinear photonic crystal fiber for broad spectral content
(Institute of Electrical and Electronics Engineers Inc., 2007) Cherif, Rim; Zghal, Mourad; Hamam, Habib
We numerically analyze the stimulated Raman scattering (SRS) in nonlinear photonic crystal fibers (PCF). Generalized nonlinear Schrodinger equation was used to model the propagation of femtosecond pulses in PCF. We demonstrate that, for a sufficiently broad spectral content, stimulated Raman scattering transfers energy from the higher frequency spectral components to lower frequencies, resulting in a continuous self-frequency shift to longer wavelengths. The obtained results show that PCF can generate relatively strong SRS and that the higher the nonlinearity, the faster the speed of soliton fission, thus the greater the number of solitons produced at the same time. The important role of Raman scattering in the generation of a broad supercontinuum is pointed out. © 2007 IEEE.
Optical generation of UWB signal : a comparative study
(Institute of Electrical and Electronics Engineers Inc., 2007) Dridi, Kais; Hamam, Habib
In this study, we present an overview on recent existing methods to generate UWB signals. Given the increasing interest in the UWB over optical fiber, special attention will be devoted to optical methods for generating UWB signals. These methods aim at ensuring a good integration of such radio signals over optical fiber with a very low cost. Some hybrid electro-optical methods will be covered before handling "all-optical" approaches. Particular attention will be given to the seven following methods: Chromatic Dispersion based approach, FBG-based approach, Optical impulse radio system, Electrooptical intensity modulator based method, Method based on XPM in an SOA, Optical FSK based method, and Spectral shaping and dispersion-induced frequency to time conversion based technique. For illustration some results will be presented. © 2007 IEEE.
Time based generation signal for UWB over fiber
(Institute of Electrical and Electronics Engineers Inc., 2007) Dridi, Kais; Hamam, Habib
We propose a new all optical fiber based Ultra-wideband (UWB) pulse generation for propagation over optical fibers (UWBoF). The approach is based on time delay. The technique consists in duplicating the input signal, shifting the two replicas in time and inverting one of them (phase opposition). By recombining the shifted replicas, we obtain the first derivative order of the initial pulse. Thus, monocycle like pulses can be generated. Several gigahertzs of bandwidths can be freely obtained fulfilling there the requirements of the Federal Communication Commission (FCC). New experimental scheme and results are presented. Using this cost-effective method, UWB signals can be easily generated and propagated over optical fiber before radiating them. © 2007 IEEE.
Space based generation signal for UWB over fiber
(Institute of Electrical and Electronics Engineers Inc., 2007) Dridi, Kais; Hamam, Habib
We propose a novel approach for generating UWB signals for propagation over the optical fiber. This technique uses the effect of chromatic dispersion in single mode fibers, expressed by the Schrodinger equation. After duplicating the input pulse signal, the interference of two replica, that are unequally dispersed, results in a second order derivate of the input signal and therefore in an UWB pulse carried by an optical wave. Gaussian doublet like signals can easily be generated. This enables providing several gigahertz bandwidths for applications in high-bit-rate UWB wireless communications. New experimental schemes are given as a proof for our new approach. This new method allows not only generating UWB pulses but also distributing them over optical fibers with a low integration cost. © 2007 IEEE.
Self-imaging based dispersion compensation : performance and tolerance of the system
(Institute of Electrical and Electronics Engineers Inc., 2007) Guizani, Sghaier; Hamam, Habib
Transmitting ultra wideband (UWB) pulse signals over optical fiber is a certain sign of Chromatic dispersion existence. (CD) is a serious problem in optical transmission because the velocity of light depends on the frequencies. The effect is strengthened when the optical pulse gets shorter because its spectrum gets broader. This results in a temporal broadening of the initial pulse. The signal is then deformed during propagation, resulting in Inter-Symbol Interference (ISI). Alteration is more pronounced if the optical signal travels further, yielding to shortening the inter-repeater distance. We propose a method for chromatic dispersion compensation. It is based on the Temporal Talbot effect that is observed when a periodic signal propagates through a dispersive medium at a given distance named Talbot distance ZT. Our method consists in adding a portion of a dispersive fiber so that the overall propagation distance corresponds to one specific distance, called a fractional Talbot distance. Because a specific length of a generally long fiber is put into play, the tolerance permitted by the approach needs particular attention © 2007 IEEE.
A modal logic for the CARE usability properties for multimodal user interfaces
(2008) Kamel, Nadjet; Selouani, Sid-Ahmed; Hamam, Habib
This paper proposes the use of model- checking technique to validate Multimodal User Interfaces (MUIs). It introduces a modal logic to express the CARE (Complementarity, Assignation, Redundancy and Equivalent) usability properties for MUIs : the LCARE modal logic. The syntax, the semantics and an axiom system for LCARE are defined. LCARE allows for the specification of the CARE usability properties that a MUI must satisfy. The model-checking technique is used to check whether a CARE property, expressed in LCARE, is satisfied by a MUI. For this purpose the user multimodal interactions are modeled by a transition system and the CARE properties are expressed in LCARE formulae. A satisfiability relation is defined. It checks whether a LCARE formula is satisfied by the transition system modeling the multimodal interactions. LCARE allows for the specification of all the CARE usability properties. An illustration is given for the Matis application (Multimodal Airline Travel Information System) as a case study.
RoF networks : a comprehensive study
(Institute of Electrical and Electronics Engineers Inc., 2008) Chettat, Hichem; Mokhtar, Simohamed Lotfy; Bouslimani, Yassine; Hamam, Habib
We present a comparative study of different Fiber-Wireless networks with regards to their applications, architecture, hardware complexity, development costs, offered services and allocated bandwidths. While spectral resources and high data-rates are incessantly requested, these Radio over Fiber (RoF) networks have been proposed to overcome limitation in bandwidth. They take advantage of the spectral potential of millimeter-waves bands. Due to their flexibility, RoF links may be designed for a transparent transport of analog or digital signals. Several applications, based on point to point or point to multi points links, are here reviewed. Trends and prospects for these networks are also explored. © 2008 IEEE.
An optimized RFID-based academic library
(Institute of Electrical and Electronics Engineers Inc., 2008) Fennani, A.; Hamam, Habib
We present a solution for integrating RFID technology in academic libraries by offering cost-effectiveness and good quality of service. On the one hand, we challenge hardware issues which include optimization of the layout of the RFID system by minimizing the total number of used devices, avoiding collision between them and capturing all tags. On other hand, the main challenge in designing powerful RFID middleware is the use of a modular and generic programming method that enables reusing some software parts in various applications, offering flexibility, to a large extent, in introducing new equipments like readers and sensors and allowing for the use of devices from different suppliers. We succeeded in developing a user-friendly application that enables full automatic management of the library as well as a test bed for real time optimizing the layout of our RFID system. © 2008 IEEE.
MULTI-STREAM FRONT-END PROCESSING FOR ROBUST DISTRIBUTED SPEECH RECOGNITION
(International Society for Computers and Their Applications (ISCA), 2008) Kifaya, Kaoukeb; Nourozian, Atta; Selouani, Sid-Ahmed; Hamam, Habib; Tolba, Hesham
A highly robust audio hashing system using auditory-based front-end processing
(Institute of Electrical and Electronics Engineers Inc., 2009) Salem, Abderraouf Ben; Selouani, Sid-Ahmed; Hamam, Habib; Caelen, Jean
In this paper, a robust perceptual audio hashing system is presented. A model of the human auditory system is used to extract robust features from the outputs of a non-linear filter bank that mimics the human basilar membrane. Experiments on various audio excerpts show that this new ear-based frontend processing provides very effective hash values. The proposed audio hashing system performs very satisfactorily in identification and it turned out very resilient to a large variety of severe audio attacks. ©2009 IEEE.
A cooperative and conversational virtual agent for M-commerce applications
(Institute of Electrical and Electronics Engineers Inc., 2009) Rekik, Siwar; Selouani, Sid-Ahmed; Hamam, Habib
The aim of this paper is to present a cooperative approach to improve the Human-System spoken dialogues. The main advantage of the proposed approach is its ability to reach both of the user and the system goals more efficiently. The strategy that underlines our system is well adapted to the mobile applications since it involves effective spoken exchanges to reach the users' and system mutual goals. The proposed fram ework is built in order to use the Hidden Markov Models (HMMs) based CMU-Sphinx speech recognition engine f or mobile communications. To evaluate our approach a case-study in the M-trading field is considered. The analysis of the case study shows the efficiency ofour strategy in comparison with the usual ones. ©2009 IEEE.
A model-checking approach for the verification of CARE usability properties for multimodal user interfaces
(Praise Worthy Prize S.r.l., 2009-01) Kamel, Nadjet; Selouani, Sid-Ahmed; Hamam, Habib
A model-checking-based approach is proposed to verify the CARE (Complementarity, Assignement, Redundancy and Equivalence) usability properties for Multimodal User Interfaces (MUIs). This approach reduces the states explosion problem which is the main inconvenience of the model-checking technique. For this, we propose to decompose the transition system describing the behaviours of the MUI into a set of transition systems, and we decompose the temporal logic formula, that specifies the CARE property, into a set of reachability property formulas. The decomposition is based on disabling a set of modalities in the system. The model-checking process of the CARE property is done through a set of stages. At each stage a reachability formula is checked on a MUI component transition system. The process is aborted if a reachability formula is not satisfied. This approach reduces the complexity of the CARE model-checking process. We illustrate this approach, using the SMV (Symbolic Model Verifier) model-checker, on a MUI of a mobile cell phone case study. © 2009 Praise Worthy Prize S.r.l. - All rights reserved.
Web-based engine for program curriculum designers
(Institute of Electrical and Electronics Engineers Inc., 2009-11) Hamam, Habib; Loucif, Samia
Educational institutions pay careful attention to the design of program curricula, which represent a framework to meet institutional goals and missions. Of course, the success of any institution depends highly on the quality of its program curriculum. The development of such a curriculum and, more importantly, the evaluation of its quality are complex and time-consuming processes. This traditional approach requires many cumbersome manual iterations, making it a long and error-prone process. To overcome these problems, this paper proposes a new curriculum support engine as an alternative approach. The proposed curriculum support engine is a Web-based application that helps in designing any program curriculum in real time. The engine incorporates several important features, allowing the verification of the proposed curriculum coherence and the generation of statistics necessary for academic and accreditation purposes. Useful viewing and editing tools are also provided. The proposed curriculum support engine is flexible and allows additional criteria that the curriculum designer can specify to be incorporated. In particular, the engine covers the Accreditation of Canadian Engineering Programs (CEAB), the Accreditation Board for Engineering and Technology (ABET), and the Commission of Academic Accreditation of the Ministry of Higher Education and Scientific Research of UAE (CAA-UAE). © 2006 IEEE.
A new hybrid frame ALOHA and binary splitting algorithm for anti-collision in RFID systems
(Institute of Electrical and Electronics Engineers Inc., 2010) Al-Medhwahi, Mohammed; Alkholidi, Abdulsalam; Hamam, Habib
Collision is considered as one of the most important issues to be in mind in RFID system designing. Although, there are many algorithms that all of them are aiming - at the end - to decrease collision state numbers or to process such states that help achieve an accurate identification process in an acceptable period of time. In this paper, we intend to propose an algorithm offering balanced performance in general and excellent performance in environments with low or medium tags population. It gives the ability to reduce the number of collisions, in the first stage, and to identify tags that failed to be identified due to the occurred collisions, in the next stage. For illustration, we present simulation showing our algorithm performance against some commonly used algorithms.
Auditory-based subband blind source separation using sample-by-sample and Infomax algorithms
(2010) Salem, Abderraouf Ben; Selouani, Sid Ahmed; Hamam, Habib
We present a new subband decomposition method for the separation of convolutive mixtures of speech. This method uses a sample-by-sample algorithm to perform the subband decomposition by mimicking the processing performed by the human ear. The unknown source signals are separated by maximizing the entropy of a transformed set of signal mixtures through the use of a gradient ascent algorithm. Experimental results show the efficiency of the proposed approach in terms of signal-to-interference ratio. Compared with the fullband method that uses the Infomax algorithm, our method shows an important improvement of the output signal-to-noise ratio when the sensor inputs are severely degraded by additive noise.
OFDM with parity bit selected block spreading
(Institute of Electrical and Electronics Engineers Inc., 2010) Moussa, Sherif; Dahmane, Adel Omar; D'Amours, Claude; Hamam, Habib
In this paper, a new scheme that combines Orthogonal Frequency Division Multiplexing (OFDM) with parity bit selected block spreading is introduced. In this proposed method, the data symbols in each block is used to select the spreading code. Therefore, frequency diversity in the system is increased as well as improving the symbol detection due to the inherent coding in the spreading technique. Simulation results show significant improvement in BER performance for the proposed system compared with conventional OFDM one. © 2009 IEEE.
Deepkover - an adaptive artful intelligent assistance system for cognitively impaired people
(Taylor and Francis Ltd., 2010) Najjar, Mehdi; Courtemanche, Francois; Hamam, Habib; Mayers, Andre
This article presents a novel modular adaptive artful intelligent assistance system for cognitively and/or memory impaired people engaged in the realisation of their activities of daily living (ADLs). The goal of this assistance system is to help disabled persons moving/evolving within a controlled environment in order to provide logistic support in achieving their ADLs. Empirical results of practical tests are presented and interpreted. Some deductions about the key features that represent originalities of the assistance system are drawn and future works are announced. © 2010 Taylor & Francis Group, LLC.
Dynamic energy based text-in-speech spectrum hiding using speech masking properties
(Institute of Electrical and Electronics Engineers Inc., 2010) Djebbar, Fatiha; Abed-Meraim, Karim; Guerchi, Driss; Hamam, Habib
In this paper we present a new method for text-in-speech Fast Fourier Transform (FFT) based steganography. Our method exploits high energetic magnitude frequency components of speech spectrum to hide the secret text. The energy level of each magnitude component is evaluated, and considered only if it is high enough to embed secret data. A frequency maskmg threshold is then calculated for each energetic frequency magnitude component to decide where to embed the secret text. As a result, the initial energy of the cover speech spectrum is slightly modified and the dIstortion error is always kept under the mask. The objective and subjective evaluations show that introducing the energy-based frequency masking 0l?ens new frontiers in text-in-speech steganography since hIgher bit rate text embedding was achieved while obtaining a stego-speech with unnoticeable distortion. © 2010 IEEE.
Text hiding in high frequency components of speech spectrum
(Institute of Electrical and Electronics Engineers Inc., 2010) Djebbar, Fatiha; Guerchi, Driss; Abed-Meraim, Karim; Hamam, Habib
Boosted by recent advances in the information technology field, methods applied to ensure privacy of digital data became very important in many real life applications. Efficient secrecy can be achieved at least in part, by implementing steganograhy techniques. In this paper, we propose a new technique to hide text in wideband speech in noise free environment. We opted to work in the Fourier transform domain and hide the digital information within high frequency components. More precisely, our method exploits selected locations from the high-frequencies part of the cover speech to hide the secret text. We better preserve with high fidelity the spectrum shape of the speech carrier by employing an embedding rather than a replacement operation on the secret text. Our simulation results show that this approach maintains the robustness of the cover signal and achieves a higher hiding capacity. © 2010 IEEE.
Intensity based self-imaging
(OSA - The Optical Society, 2010) Hamam, Habib
We propose an iterative method to optimize the phase profile of the initial field so that its intensity profile is observed periodically along the longitudinal (propagation) axis. The new method is inspired from the Gerchberg-Saxton technique, where the Fresnel transform is used, instead of the Fourier transform, for retrieving the phase profile of several light distributions (for example, 15 planes), instead of a Fourier pair of distributions. The additional challenge, with respect to the conventional Gerchberg-Saxton technique, is that the planes where constraints are applied number more than two. It turned out that when the number of periods increased, the spectrum of the obtained initial field converges toward including Montgomery's rings (self-imaging condition). © 2010 Optical Society of America.

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