The initiating explosive shock environment of an aerospace mission has the characteristics of ins... more The initiating explosive shock environment of an aerospace mission has the characteristics of instantaneity, high amplitude and a wide frequency domain. An improved method based on the acceleration frequency response function (FRF) and virtual mode synthesis method (VMSS) is proposed to predict the pyroshock response of a spacecraft structure in a wide frequency domain. Firstly, the statistical energy analysis (SEA) model of the spacecraft structure was established, and the FRF and modal density of the model were obtained. Then, the paper explains how, due to the small number of modes in the low-frequency band, the calculation results of the SEA method in the low-frequency band were not accurate enough. The FRF of the SEA model in the low-frequency band was modified by an FRF test of the structure. Finally, the shock response spectrum (SRS) was obtained based on the VMSS and the modified FRF. A shock experiment on the spacecraft structure was conducted by using the shock experiment ...
IEEE 802.22 wireless regional area network (WRAN) is an emerging cognitive radio-based system. On... more IEEE 802.22 wireless regional area network (WRAN) is an emerging cognitive radio-based system. One of the major challenges for WRANs is how to efficiently schedule both channel sensing and data transmission for multiple adjacent WRAN cells. This challenge is known as coexistence problem. In this paper, we propose four schemes that aim at reducing the coexistence-problem effect. These schemes are based on a well-known operation mode of IEEE 802.22, namely dynamic frequency hopping (DFH). The first and second schemes are based on using omni-directional antennas at the base stations (BSs), whereas the BSs in the other two schemes use directional antennas. The first scheme, coined fixed-scheduling DFH (FDFH), bases upon a fixed scheduling of working channels for adjacent WRAN cells. The second scheme, called cooperative DFH (CDFH), cooperatively selects working channels. The third scheme, namely sectoral DFH (SDFH), is proposed to reduce the coordination overhead of CDFH via dividing a WRAN cell into sectors to decrease the chances of collisions between adjacent cells. Finally, we integrate FDFH and SDFH into a new scheme, called fixed-scheduling sectoral DFH (FSDFH), which exploits the advantages of both schemes with no additional overhead. Computer simulations are used to demonstrate the performance gain of the proposed schemes.
2014 37th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), 2014
ABSTRACT The use of user identification technology has become increasingly in demand in today&... more ABSTRACT The use of user identification technology has become increasingly in demand in today's society. Biometrics have been capitalized upon for this purpose. The human iris in particular is one of the most unique and intriguing biometrics available to use in the identification of an individual. The process of recognizing a human iris is split into four major steps. These steps are segmentation, normalization, feature extraction, and matching. In this paper, two new methods are introduced to implement feature extraction. Both methods use a sliding-window technique and different mathematical operations on the pixels to produce feature vectors. Experimental results of the methods produced relatively small feature vectors of size 5×120 and 5×130. A small feature vector is valuable as it contributes to the efficiency and speed of the overall recognition system. In addition, a step was included in both methods to minimize the effect of varying light intensity. This reduces the time needed to acquire an image with suitable lighting, which in turn contributes to the speed of the system as well. Analysis of our methods was done by considering various performance metrics such as the False Acceptance Rate (FAR), False Rejection Rate (FRR), and Recognition Rate (RR). Both proposed methods achieved a recognition rate of about 98.3264%.
2014 37th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), 2014
ABSTRACT With the development of internet technologies and communication services, message transm... more ABSTRACT With the development of internet technologies and communication services, message transmissions over the internet still have to face all kinds of security problems. Hence, how to protect secret messages during transmission becomes a challenging issue for most of the researchers. It is worth mentioning that many applications in computer science and other related fields rely on steganography and watermarking techniques to ensure information safety during communication. In this paper, we propose a new steganographic method to embed the secret data inside a cover image based on least-significant-bit (LSB) replacement method. The embedding process predominantly concentrates on distributing the secret message inside one share of a color image to appear like a 3D geometric shape. The dimensions of the geometric shape are variable pursuant to the size of secret message. Data distribution process makes our method to be of a great interest as of being so difficult for the hackers or intruders to reconstruct the shape from stego-images, thereby the security is improved. Furthermore, we compare the performance of our approach with two other relevant approaches in terms of peak signal-to-noise ratio (PSNR). The contribution of our approach was immensely impressive.
2014 IEEE 11th International Multi-Conference on Systems, Signals & Devices (SSD14), 2014
ABSTRACT A system that automatically recognizes individuals based on biometric traits has been an... more ABSTRACT A system that automatically recognizes individuals based on biometric traits has been an attractive goal for researchers for a long time. Iris recognition is a biometric identification method that combines computer vision and pattern recognition. It produces one of the most accurate methods available for security systems because of the uniqueness of the human iris. The process of iris recognition is split into 4 major steps. These steps are: Iris segmentation, normalization, feature extraction, and matching. This paper focuses on the step of feature extraction and encoding. A new method is proposed to extract features from the iris image. The method uses a sliding window technique and mathematical operations on the pixels to produce a feature vector. Experimental results of the method produced a relatively small feature vector of size 5×120, which contributes to the efficiency and speed of an iris recognition system, as well as reducing the amount of memory needed. The algorithm written for the method also includes a step to eliminate the effect of varying light intensity, which improves the accuracy of the overall system as well as reduces the time needed to acquire an image with suitable lighting. Other techniques to unify the level of light intensity among all images were applied as well. Evaluation of the method was done by considering various performance metrics such as the false acceptance rate (FAR), false rejection rate (FRR), and the recognition rate of the algorithm. The recognition rate achieved from the proposed method was about 98.54%.
Ultra-wideband (UWB) communications has emerged as a promising technology for high data rate wire... more Ultra-wideband (UWB) communications has emerged as a promising technology for high data rate wireless personal area networks (WPANs). In this paper, we address a key issue that impacts the performance of multi-hop, multi-rate UWB-based WPANs, namely joint routing and rate selection. Arbitrary selection of routes (including direct links) and transmission rates along these routes results in unnecessarily long channel reservation
2012 IEEE International Conference on Communications (ICC), 2012
ABSTRACT Opportunistic routing has recently been proposed for ad hoc networks. Several works show... more ABSTRACT Opportunistic routing has recently been proposed for ad hoc networks. Several works showed that opportunistic routing improves network performance. None of these works, however, studied the integration of opportunistic routing into multi-rate ad hoc networks. In this paper, we study this integration. Specifically, we consider the problem of determining the required number of retransmissions in opportunistic routing and the transmission rate in each retransmission such that the required (re)transmission time for a sent packet is minimized while at the same time a target end-to-end PER is satisfied. We show that this problem is NP-hard. Accordingly, we propose an approximate solution called Opportunistic routing Over Multi-rate Multi-hop ad hoc networks (OOMM). Extensive simulations over a multi-rate OFDM-based UWB network show that OOMM achieves high performance relative to different routing techniques (21%-48% throughput improvement).
The initiating explosive shock environment of an aerospace mission has the characteristics of ins... more The initiating explosive shock environment of an aerospace mission has the characteristics of instantaneity, high amplitude and a wide frequency domain. An improved method based on the acceleration frequency response function (FRF) and virtual mode synthesis method (VMSS) is proposed to predict the pyroshock response of a spacecraft structure in a wide frequency domain. Firstly, the statistical energy analysis (SEA) model of the spacecraft structure was established, and the FRF and modal density of the model were obtained. Then, the paper explains how, due to the small number of modes in the low-frequency band, the calculation results of the SEA method in the low-frequency band were not accurate enough. The FRF of the SEA model in the low-frequency band was modified by an FRF test of the structure. Finally, the shock response spectrum (SRS) was obtained based on the VMSS and the modified FRF. A shock experiment on the spacecraft structure was conducted by using the shock experiment ...
IEEE 802.22 wireless regional area network (WRAN) is an emerging cognitive radio-based system. On... more IEEE 802.22 wireless regional area network (WRAN) is an emerging cognitive radio-based system. One of the major challenges for WRANs is how to efficiently schedule both channel sensing and data transmission for multiple adjacent WRAN cells. This challenge is known as coexistence problem. In this paper, we propose four schemes that aim at reducing the coexistence-problem effect. These schemes are based on a well-known operation mode of IEEE 802.22, namely dynamic frequency hopping (DFH). The first and second schemes are based on using omni-directional antennas at the base stations (BSs), whereas the BSs in the other two schemes use directional antennas. The first scheme, coined fixed-scheduling DFH (FDFH), bases upon a fixed scheduling of working channels for adjacent WRAN cells. The second scheme, called cooperative DFH (CDFH), cooperatively selects working channels. The third scheme, namely sectoral DFH (SDFH), is proposed to reduce the coordination overhead of CDFH via dividing a WRAN cell into sectors to decrease the chances of collisions between adjacent cells. Finally, we integrate FDFH and SDFH into a new scheme, called fixed-scheduling sectoral DFH (FSDFH), which exploits the advantages of both schemes with no additional overhead. Computer simulations are used to demonstrate the performance gain of the proposed schemes.
2014 37th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), 2014
ABSTRACT The use of user identification technology has become increasingly in demand in today&... more ABSTRACT The use of user identification technology has become increasingly in demand in today's society. Biometrics have been capitalized upon for this purpose. The human iris in particular is one of the most unique and intriguing biometrics available to use in the identification of an individual. The process of recognizing a human iris is split into four major steps. These steps are segmentation, normalization, feature extraction, and matching. In this paper, two new methods are introduced to implement feature extraction. Both methods use a sliding-window technique and different mathematical operations on the pixels to produce feature vectors. Experimental results of the methods produced relatively small feature vectors of size 5×120 and 5×130. A small feature vector is valuable as it contributes to the efficiency and speed of the overall recognition system. In addition, a step was included in both methods to minimize the effect of varying light intensity. This reduces the time needed to acquire an image with suitable lighting, which in turn contributes to the speed of the system as well. Analysis of our methods was done by considering various performance metrics such as the False Acceptance Rate (FAR), False Rejection Rate (FRR), and Recognition Rate (RR). Both proposed methods achieved a recognition rate of about 98.3264%.
2014 37th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), 2014
ABSTRACT With the development of internet technologies and communication services, message transm... more ABSTRACT With the development of internet technologies and communication services, message transmissions over the internet still have to face all kinds of security problems. Hence, how to protect secret messages during transmission becomes a challenging issue for most of the researchers. It is worth mentioning that many applications in computer science and other related fields rely on steganography and watermarking techniques to ensure information safety during communication. In this paper, we propose a new steganographic method to embed the secret data inside a cover image based on least-significant-bit (LSB) replacement method. The embedding process predominantly concentrates on distributing the secret message inside one share of a color image to appear like a 3D geometric shape. The dimensions of the geometric shape are variable pursuant to the size of secret message. Data distribution process makes our method to be of a great interest as of being so difficult for the hackers or intruders to reconstruct the shape from stego-images, thereby the security is improved. Furthermore, we compare the performance of our approach with two other relevant approaches in terms of peak signal-to-noise ratio (PSNR). The contribution of our approach was immensely impressive.
2014 IEEE 11th International Multi-Conference on Systems, Signals & Devices (SSD14), 2014
ABSTRACT A system that automatically recognizes individuals based on biometric traits has been an... more ABSTRACT A system that automatically recognizes individuals based on biometric traits has been an attractive goal for researchers for a long time. Iris recognition is a biometric identification method that combines computer vision and pattern recognition. It produces one of the most accurate methods available for security systems because of the uniqueness of the human iris. The process of iris recognition is split into 4 major steps. These steps are: Iris segmentation, normalization, feature extraction, and matching. This paper focuses on the step of feature extraction and encoding. A new method is proposed to extract features from the iris image. The method uses a sliding window technique and mathematical operations on the pixels to produce a feature vector. Experimental results of the method produced a relatively small feature vector of size 5×120, which contributes to the efficiency and speed of an iris recognition system, as well as reducing the amount of memory needed. The algorithm written for the method also includes a step to eliminate the effect of varying light intensity, which improves the accuracy of the overall system as well as reduces the time needed to acquire an image with suitable lighting. Other techniques to unify the level of light intensity among all images were applied as well. Evaluation of the method was done by considering various performance metrics such as the false acceptance rate (FAR), false rejection rate (FRR), and the recognition rate of the algorithm. The recognition rate achieved from the proposed method was about 98.54%.
Ultra-wideband (UWB) communications has emerged as a promising technology for high data rate wire... more Ultra-wideband (UWB) communications has emerged as a promising technology for high data rate wireless personal area networks (WPANs). In this paper, we address a key issue that impacts the performance of multi-hop, multi-rate UWB-based WPANs, namely joint routing and rate selection. Arbitrary selection of routes (including direct links) and transmission rates along these routes results in unnecessarily long channel reservation
2012 IEEE International Conference on Communications (ICC), 2012
ABSTRACT Opportunistic routing has recently been proposed for ad hoc networks. Several works show... more ABSTRACT Opportunistic routing has recently been proposed for ad hoc networks. Several works showed that opportunistic routing improves network performance. None of these works, however, studied the integration of opportunistic routing into multi-rate ad hoc networks. In this paper, we study this integration. Specifically, we consider the problem of determining the required number of retransmissions in opportunistic routing and the transmission rate in each retransmission such that the required (re)transmission time for a sent packet is minimized while at the same time a target end-to-end PER is satisfied. We show that this problem is NP-hard. Accordingly, we propose an approximate solution called Opportunistic routing Over Multi-rate Multi-hop ad hoc networks (OOMM). Extensive simulations over a multi-rate OFDM-based UWB network show that OOMM achieves high performance relative to different routing techniques (21%-48% throughput improvement).
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Papers by Raed Alzubi