M. Aboul-dahab - Academia.edu (original) (raw)

Papers by M. Aboul-dahab

A cryptographic hash function has an important role in cryptography to achieve certain security g... more A cryptographic hash function has an important role in cryptography to achieve certain security goals such as authenticity, digital signatures, digital time stamping, and entity authentication. They are also strongly related to other important cryptographic tools such as block ciphers and pseudorandom functions.Due to the previous merits we present a proposal for a new secure hash algorithm based on the combination of some functions of SHA-256 (Secure Hash Algorithm 256)-with its message expansion modification- and MD5 (Message Digest 5) based on double-Davis-Mayer scheme to overcome the weakness existing in these functions. The proposal hash algorithm has been designed to satisfy the different levels of enhanced security and to resist the advanced hash attacks by increasing the complexity degree of the proposed hash algorithm. The security analysis of the proposed hash algorithm is compared to SHA256 and gives more security and highly acceptable results as shown in our security res...

Proceedings of the Twenty-First National Radio Science Conference, 2004. NRSC 2004., 2004

Space-time block coding (STBC) is a signaling algorithm utilizing multiple transmit and receive a... more Space-time block coding (STBC) is a signaling algorithm utilizing multiple transmit and receive antennas in order to improve the system performance and increase the channel capacity in the presence of fading and interference. This paper introduces Prerake space-time block codes (PRK-STBC) for multiuser direct-sequence code-division multiple-access (DS-CDMA) systems operating in time-division-duplex (TDD) mode. PRK-STBC combines both antenna diversity and temporal precoding. In a DS-CDMA system, the transmit antennas are available to all users at all the time. In a multipath channel, the prerake coding of the transmitted signals results in multipath diversity, without the need of rake receivers at the mobile stations. Hence, only simplified mobile receivers are needed and most of the signal processing is done at the base station. The performance of PRK-STBC is examined in multipath fading. The performance is also investigated against the used number of transmit and receive antennas (up to four transmit antennas and one receive antenna are considered in the simulation).

Proceedings of the Twenty-Second National Radio Science Conference, 2005. NRSC 2005., 2005

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109), 1998

... Moh:smed A. Aboul-Dahab*, Senior Member IEEE, Khalid A. Hijjah* and Said E. El-Khamy&... more ... Moh:smed A. Aboul-Dahab*, Senior Member IEEE, Khalid A. Hijjah* and Said E. El-Khamy" *, Senior Member KEEE. * Dept. ... Each of these components is applied to a “4. The output of the W's is the resultant array pattern, which is aimed to have very deep side lobe levels. ...

IEEE Antennas and Propagation Society Symposium, 2004., 2004

Page 1. Fractal Multiband Antennas Using GMMOM Optimized Log Periodic Dipole Arrays Said E. El-Kh... more Page 1. Fractal Multiband Antennas Using GMMOM Optimized Log Periodic Dipole Arrays Said E. El-Khamy *and Mohab A. Mangoud ", Mohamed A. Aboul-Dahab ", Amira I. Zaki ' *Deet. of Elect. Eng., Fac. ofEng., Alexandria ...

2003 46th Midwest Symposium on Circuits and Systems, 2003

... 4 2 =h; .r, -h,.r2 =(a + a)2 - h,.n; + hn ) ... TuRBo CODE Turbo codes were introduced in 199... more ... 4 2 =h; .r, -h,.r2 =(a + a)2 - h,.n; + hn ) ... TuRBo CODE Turbo codes were introduced in 1993 by Claude Berrou, Alain Glavieux and Punya Thitimajshima [7], [8]. Turbo codes are constructed from the parallel concatenation of two recessive systematic convolutional RSC codes. ...

2003 46th Midwest Symposium on Circuits and Systems, 2003

Antennas and Propagation, …, 1991

... lY66. SE El-Khamy and MA Aboul-Dahab “On The Performance of Antimultipath Adaptive Antenna Ar... more ... lY66. SE El-Khamy and MA Aboul-Dahab “On The Performance of Antimultipath Adaptive Antenna Arrays,” presented at the Int. symposium on Antennas (JINA.90) France. ... I I II SUhOptiMUM ---- OptiMUM Fig.4 Optimum and suboptimum array patterns for a fifteen elements array.

… , 2009. NRSC 2009. …, 2009

Page 1. March 17-19,2009, Faculty of Engineering, Future Univ., Egypt 26th NATIONAL RADIO SCIENCE... more Page 1. March 17-19,2009, Faculty of Engineering, Future Univ., Egypt 26th NATIONAL RADIO SCIENCE CONFERENCE (NRSC2009) ~ A Hybrid of Particle Swarm Optimization and Genetic Algorithm for Multicarrier Cognitive ...

Proceedings of the Seventeenth National Radio Science Conference. 17th NRSC'2000 (IEEE Cat. No.00EX396), 2000

... Mohamed A. Aboul-Dahab*, Senior IEEE, Maged I. Elkashlan', Student member IE... more ... Mohamed A. Aboul-Dahab*, Senior IEEE, Maged I. Elkashlan', Student member IEEE ... The objective of antenna synthesis is to spec@ a desired radiation pattern to arrive at an antenna configuration that produces a pattern that acceptably approximates the desired pattem [I]. The ...

WIT Transactions on Information and Communication Technologies, 1970

The principles underlying the transmission or reception of electromagnetic energy by an antenna i... more The principles underlying the transmission or reception of electromagnetic energy by an antenna is based on relationships between electrical and magnetic fields, which can be described by Maxwell's equations. The directional characteristics of the antenna are best understood from its radiation pattern which is a 3 dimensional plot of the radiated or received fields. In this paper, the students are oriented towards utilizing some computational graphics techniques which enable them to implement their own software packages that can help in visualizing the antenna radiation patterns.

The paper discusses a new design of RFID reader antenna. The proposed antenna is operating in UHF... more The paper discusses a new design of RFID reader antenna. The proposed antenna is operating in UHF Band (902–928 MHz), which is one of the bands used for RFID applications. Various techniques are used for enhancing the antenna parameters, to achieve compact size, increase the bandwidth and ensure circular polarization. Matching is achieved by choosing the appropriate point for feeding instead of using a reactive matching circuit. Increasing the axial ratio bandwidth to maintain circular polarization transmission and reception is done by using different slot sizes and positions, alongside slits. These slots and slits on the patch lead to the increase of the −10 dB impedance bandwidth to cover the whole bandwidth required for RFID applications. The slits also reduce the antenna size to around 87% of the conventional patch. In order to add another benefit to the design, FR4 is used as the dielectric substrate to decrease the cost. However, this means the size can be further reduced usin...

Article history: Received 8 July 2017 Received in revised form 24 October 2017 Accepted 4 Decembe... more Article history: Received 8 July 2017 Received in revised form 24 October 2017 Accepted 4 December 2017 Available online 24 March 2018 This paper focuses on absorption by metal nanoantennas as a means to enhance light trapping into thin-film solar cells. It determines the optimum metal nanoantennas distribution for solar cell applications, taking into account interactions between the particles as well as including the interaction with the absorbing substrate. Tapered structure is proposed for absorption enhancement using different metal nanoantennas like gold, silver, copper and aluminium. The sizes of nanoantennas are tapered in one direction. The tapered structures are composed of an array of metal nanoantennas and the sizes are tapered using two different ways according to a tapering direction. The degree of tapering can be set by controlling a scaling element. All simulation data are obtained using finite element method. Larger than 20% increase in the absorption can be achieved.

IOP Conference Series: Materials Science and Engineering

International journal of Computer Networks & Communications

The International Conference on Electrical Engineering

Proceedings of the Seventeenth National Radio Science Conference. 17th NRSC'2000 (IEEE Cat. No.00EX396), 2000

In a mobile communication environment the received signals are corrupted with noise in the commun... more In a mobile communication environment the received signals are corrupted with noise in the communication channel. This noise can be modeled mathematically according to the channel characteristics by one of several channel models. In this paper, a channel model estimator based on the Chi-square test is presented. This estimator recognizes an appropriate statistical channel model based on the best matched

Proceedings of the 43rd IEEE Midwest Symposium on Circuits and Systems (Cat.No.CH37144), 2000

Page 1. CMOS Implementation of a Digital Viterbi System Hazem H. Ali, M. Aboul-Dahab, Hatem M. El... more Page 1. CMOS Implementation of a Digital Viterbi System Hazem H. Ali, M. Aboul-Dahab, Hatem M. El matbouly, Mohammad A. El sayed, Ahmad M. Zalat Dept. of Electronics & Communications engineering Arab Academy for Science & Technology ...

A cryptographic hash function has an important role in cryptography to achieve certain security g... more A cryptographic hash function has an important role in cryptography to achieve certain security goals such as authenticity, digital signatures, digital time stamping, and entity authentication. They are also strongly related to other important cryptographic tools such as block ciphers and pseudorandom functions.Due to the previous merits we present a proposal for a new secure hash algorithm based on the combination of some functions of SHA-256 (Secure Hash Algorithm 256)-with its message expansion modification- and MD5 (Message Digest 5) based on double-Davis-Mayer scheme to overcome the weakness existing in these functions. The proposal hash algorithm has been designed to satisfy the different levels of enhanced security and to resist the advanced hash attacks by increasing the complexity degree of the proposed hash algorithm. The security analysis of the proposed hash algorithm is compared to SHA256 and gives more security and highly acceptable results as shown in our security res...

Proceedings of the Twenty-First National Radio Science Conference, 2004. NRSC 2004., 2004

Space-time block coding (STBC) is a signaling algorithm utilizing multiple transmit and receive a... more Space-time block coding (STBC) is a signaling algorithm utilizing multiple transmit and receive antennas in order to improve the system performance and increase the channel capacity in the presence of fading and interference. This paper introduces Prerake space-time block codes (PRK-STBC) for multiuser direct-sequence code-division multiple-access (DS-CDMA) systems operating in time-division-duplex (TDD) mode. PRK-STBC combines both antenna diversity and temporal precoding. In a DS-CDMA system, the transmit antennas are available to all users at all the time. In a multipath channel, the prerake coding of the transmitted signals results in multipath diversity, without the need of rake receivers at the mobile stations. Hence, only simplified mobile receivers are needed and most of the signal processing is done at the base station. The performance of PRK-STBC is examined in multipath fading. The performance is also investigated against the used number of transmit and receive antennas (up to four transmit antennas and one receive antenna are considered in the simulation).

Proceedings of the Twenty-Second National Radio Science Conference, 2005. NRSC 2005., 2005

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109), 1998

... Moh:smed A. Aboul-Dahab*, Senior Member IEEE, Khalid A. Hijjah* and Said E. El-Khamy&... more ... Moh:smed A. Aboul-Dahab*, Senior Member IEEE, Khalid A. Hijjah* and Said E. El-Khamy" *, Senior Member KEEE. * Dept. ... Each of these components is applied to a “4. The output of the W's is the resultant array pattern, which is aimed to have very deep side lobe levels. ...

IEEE Antennas and Propagation Society Symposium, 2004., 2004

Page 1. Fractal Multiband Antennas Using GMMOM Optimized Log Periodic Dipole Arrays Said E. El-Kh... more Page 1. Fractal Multiband Antennas Using GMMOM Optimized Log Periodic Dipole Arrays Said E. El-Khamy *and Mohab A. Mangoud ", Mohamed A. Aboul-Dahab ", Amira I. Zaki ' *Deet. of Elect. Eng., Fac. ofEng., Alexandria ...

2003 46th Midwest Symposium on Circuits and Systems, 2003

... 4 2 =h; .r, -h,.r2 =(a + a)2 - h,.n; + hn ) ... TuRBo CODE Turbo codes were introduced in 199... more ... 4 2 =h; .r, -h,.r2 =(a + a)2 - h,.n; + hn ) ... TuRBo CODE Turbo codes were introduced in 1993 by Claude Berrou, Alain Glavieux and Punya Thitimajshima [7], [8]. Turbo codes are constructed from the parallel concatenation of two recessive systematic convolutional RSC codes. ...

2003 46th Midwest Symposium on Circuits and Systems, 2003

Antennas and Propagation, …, 1991

... lY66. SE El-Khamy and MA Aboul-Dahab “On The Performance of Antimultipath Adaptive Antenna Ar... more ... lY66. SE El-Khamy and MA Aboul-Dahab “On The Performance of Antimultipath Adaptive Antenna Arrays,” presented at the Int. symposium on Antennas (JINA.90) France. ... I I II SUhOptiMUM ---- OptiMUM Fig.4 Optimum and suboptimum array patterns for a fifteen elements array.

… , 2009. NRSC 2009. …, 2009

Page 1. March 17-19,2009, Faculty of Engineering, Future Univ., Egypt 26th NATIONAL RADIO SCIENCE... more Page 1. March 17-19,2009, Faculty of Engineering, Future Univ., Egypt 26th NATIONAL RADIO SCIENCE CONFERENCE (NRSC2009) ~ A Hybrid of Particle Swarm Optimization and Genetic Algorithm for Multicarrier Cognitive ...

Proceedings of the Seventeenth National Radio Science Conference. 17th NRSC'2000 (IEEE Cat. No.00EX396), 2000

... Mohamed A. Aboul-Dahab*, Senior IEEE, Maged I. Elkashlan', Student member IE... more ... Mohamed A. Aboul-Dahab*, Senior IEEE, Maged I. Elkashlan', Student member IEEE ... The objective of antenna synthesis is to spec@ a desired radiation pattern to arrive at an antenna configuration that produces a pattern that acceptably approximates the desired pattem [I]. The ...

WIT Transactions on Information and Communication Technologies, 1970

The principles underlying the transmission or reception of electromagnetic energy by an antenna i... more The principles underlying the transmission or reception of electromagnetic energy by an antenna is based on relationships between electrical and magnetic fields, which can be described by Maxwell's equations. The directional characteristics of the antenna are best understood from its radiation pattern which is a 3 dimensional plot of the radiated or received fields. In this paper, the students are oriented towards utilizing some computational graphics techniques which enable them to implement their own software packages that can help in visualizing the antenna radiation patterns.

The paper discusses a new design of RFID reader antenna. The proposed antenna is operating in UHF... more The paper discusses a new design of RFID reader antenna. The proposed antenna is operating in UHF Band (902–928 MHz), which is one of the bands used for RFID applications. Various techniques are used for enhancing the antenna parameters, to achieve compact size, increase the bandwidth and ensure circular polarization. Matching is achieved by choosing the appropriate point for feeding instead of using a reactive matching circuit. Increasing the axial ratio bandwidth to maintain circular polarization transmission and reception is done by using different slot sizes and positions, alongside slits. These slots and slits on the patch lead to the increase of the −10 dB impedance bandwidth to cover the whole bandwidth required for RFID applications. The slits also reduce the antenna size to around 87% of the conventional patch. In order to add another benefit to the design, FR4 is used as the dielectric substrate to decrease the cost. However, this means the size can be further reduced usin...

Article history: Received 8 July 2017 Received in revised form 24 October 2017 Accepted 4 Decembe... more Article history: Received 8 July 2017 Received in revised form 24 October 2017 Accepted 4 December 2017 Available online 24 March 2018 This paper focuses on absorption by metal nanoantennas as a means to enhance light trapping into thin-film solar cells. It determines the optimum metal nanoantennas distribution for solar cell applications, taking into account interactions between the particles as well as including the interaction with the absorbing substrate. Tapered structure is proposed for absorption enhancement using different metal nanoantennas like gold, silver, copper and aluminium. The sizes of nanoantennas are tapered in one direction. The tapered structures are composed of an array of metal nanoantennas and the sizes are tapered using two different ways according to a tapering direction. The degree of tapering can be set by controlling a scaling element. All simulation data are obtained using finite element method. Larger than 20% increase in the absorption can be achieved.

IOP Conference Series: Materials Science and Engineering

International journal of Computer Networks & Communications

The International Conference on Electrical Engineering

Proceedings of the Seventeenth National Radio Science Conference. 17th NRSC'2000 (IEEE Cat. No.00EX396), 2000

In a mobile communication environment the received signals are corrupted with noise in the commun... more In a mobile communication environment the received signals are corrupted with noise in the communication channel. This noise can be modeled mathematically according to the channel characteristics by one of several channel models. In this paper, a channel model estimator based on the Chi-square test is presented. This estimator recognizes an appropriate statistical channel model based on the best matched

Proceedings of the 43rd IEEE Midwest Symposium on Circuits and Systems (Cat.No.CH37144), 2000

Page 1. CMOS Implementation of a Digital Viterbi System Hazem H. Ali, M. Aboul-Dahab, Hatem M. El... more Page 1. CMOS Implementation of a Digital Viterbi System Hazem H. Ali, M. Aboul-Dahab, Hatem M. El matbouly, Mohammad A. El sayed, Ahmad M. Zalat Dept. of Electronics & Communications engineering Arab Academy for Science & Technology ...