Salwa Abd-el-hafiz | Cairo University (original) (raw)
Papers by Salwa Abd-el-hafiz
2016 13th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), 2016
In this paper, a generalized scheme for synchronizing a fractional order chaotic system with anot... more In this paper, a generalized scheme for synchronizing a fractional order chaotic system with another one or with a linear combination of two other fractional order chaotic systems is presented. Static (time-independent) or dynamic (time-dependent) synchronization that could generate multiple scaled versions of the response is discussed for some fractional order continuous chaotic systems based on differential equations. Non-Standard finite difference method suitable for fractional order chaotic systems is used to solve each system and get the responses. Analysis in the generalized fractional order case is presented, as well as results of simulations that match the corresponding analysis for different values of fractional order parameters.
A Knowledge-Based Approach to Program Understanding, 1995
IEEE Transactions on Magnetics, 2006
Extensive efforts have been long directed towards the development of shape optimization methodolo... more Extensive efforts have been long directed towards the development of shape optimization methodologies for electromagnetic devices. In case of devices involving nonlinear magnetic media, this optimization process becomes more complicated. This paper demonstrates how shape optimization and field analysis of such devices may be carried out efficiently and conveniently using the particle swarm evolutionary approach and without the involvement of other computational tools. Details of the proposed approach, its application to different electromagnetic devices, and comparisons with finite-element computations are presented in the paper.
IEEE Transactions on Magnetics, 2006
Vector hysteresis models are regarded as helpful tools that can be utilized in the simulation of ... more Vector hysteresis models are regarded as helpful tools that can be utilized in the simulation of multidimensional field-media interactions. Recently, substantial efforts have been focused on the refinement of vector Preisach-type models of hysteresis. The purpose of this paper is to present a computationally efficient vector Preisach-type hysteresis model constructed from only two scalar models having orthogonally interrelated elementary operators. Such a model is implemented via a linear neural network (LNN) fed from the outputs of discrete Hopfield neural network (DHNN) blocks having step activation functions. With this DHNN-LNN configuration, it is possible to carry out the identification process using well-established widely available algorithms. Details of the model, its identification, and experimental testing are presented.
IEEE Transactions on Magnetics, 2010
Accurate evaluation of ambient magnetic low-frequency fields is of great importance to several bi... more Accurate evaluation of ambient magnetic low-frequency fields is of great importance to several biological, noise, and compatibility applications. Due to their low cost, fluxmeters are regarded among the most commonly used devices for those measurement purposes. It is known that a fluxmeter can never resolve local field distributions within its sense coil dimensions. This paper introduces a new wavelet-based approach using which local field values from large sense coil fluxmeter measurements can be inferred. In this approach, wavelets on a bounded interval are used as basis functions for the efficient and accurate solution of the device response integral equation. Details and testing of the approach, in one and two dimensions, are given in the paper. Index Terms-First-kind integral equations, magnetic field measurement, method of moments (MoM), wavelets.
Abstract-This paper presents a knowledge-based analysis approach that generates first order predi... more Abstract-This paper presents a knowledge-based analysis approach that generates first order predicate logic annotations of loops. A classification of loops according to their complexity levels is presented. Based on this taxonomy, variations on the basic analysis approach that best fit each of the different classes are described. In general, mechanical annotation of loops is performed by first decomposing them using data flow analysis. This decomposition encapsulates closely related statements in events, that can be analyzed individually. Specifications of the resulting loop events are then obtained by utilizing patterns, called plans, stored in a knowledge base. Finally, a consistent and rigorous functional abstraction of the whole loop is synthesized from the specifications of its individual events. To test the analysis techniques and to assess their effectiveness, a case study was performed on an existing program of reasonable size. Results concerning the analyzed loops and the p...
Journal of Advanced Research, 2014
Magnetic materials are considered as crucial components for a wide range of products and devices.... more Magnetic materials are considered as crucial components for a wide range of products and devices. Usually, complexity of such materials is defined by their permeability classification and coupling extent to non-magnetic properties. Hence, development of models that could accurately simulate the complex nature of these materials becomes crucial to the multi-dimensional field-media interactions and computations. In the past few decades, artificial neural networks (ANNs) have been utilized in many applications to perform miscellaneous tasks such as identification, approximation, optimization, classification and forecasting. The purpose of this review article is to give an account of the utilization of ANNs in modeling as well as field computation involving complex magnetic materials. Mostly used ANN types in magnetics, advantages of this usage, detailed implementation methodologies as well as numerical examples are given in the paper. ª 2013 Production and hosting by Elsevier B.V. on behalf of Cairo University.
Journal of Advanced Research, 2015
Journal of Magnetism and Magnetic Materials, 2004
This paper presents an automated particle swarm optimization approach using which field computati... more This paper presents an automated particle swarm optimization approach using which field computations may be carried out in devices involving non-linear magnetic media. Among the advantages of the proposed approach are its ability to handle complex geometries and its computational efficiency. The proposed approach has been implemented and computations were carried out for an electromagnet subject to different DC excitation conditions. These computations showed good agreement with the results obtained by the finite-element approach.
Journal of Magnetism and Magnetic Materials, 2003
Magnetostriction models are indispensable to different crucial computational activities such as t... more Magnetostriction models are indispensable to different crucial computational activities such as those dealing with active vibration damping devices and optimum clamping stresses for transformer sheets. This paper presents an efficient magnetostriction Preisach-type model based on the effective field approach. According to this approach, the total applied field may be regarded as a super position of the actual magnetic field and
Journal of Applied Physics, 2000
It has been recently shown that the identification process of scalar, as well as some family of v... more It has been recently shown that the identification process of scalar, as well as some family of vector, Preisach-type models may be accomplished by the aid of artificial neural networks. Our purpose in this article is to further generalize the approach through which neural networks may be utilized for the identification of vector Preisach models, while using arbitrary measured data
IEEE Transactions on Magnetics, 2000
Reluctance motors are currently being used widely in different applications. Sometimes, the rotor... more Reluctance motors are currently being used widely in different applications. Sometimes, the rotor inherent saliency may introduce some difficulty in pursuing an analytical solution to the motor electromagnetic field problem. In this paper, Hopfield artificial neural networks are used to minimize the air-gap magnetic energy function. Thus, a numerical electromagnetic field solution is obtained automatically. Performance of the motor may
IEEE Transactions on Magnetics, 1998
Multimedia Tools and Applications, 2018
This paper proposes a generalized modified chaotic transition map with three independent paramete... more This paper proposes a generalized modified chaotic transition map with three independent parameters. A hardware speech encryption scheme utilizing this map along with a bit permutation network is presented. While the transition map’s generalization introduces additional parameters, the modification enhances its chaotic properties and overcomes the finite range of the control parameter and dynamical degradation problems. The modification also presents a simplification for the hardware realization of the exponentiation operation in the map’s equation because the modified output range allows conversion from the linear domain to the Logarithmic Number System (LNS). Mathematical analysis of the map is presented, where exact nonlinear expressions of the dependent parameters are derived and validated through simulations. To further simplify the hardware realization, the complicated nonlinear expressions are linearized and the introduced approximation error is quite acceptable. The encryption scheme is simulated using Xilinx ISE 14.7 and realized on Xilinx Nexys 4 Artix-7 FPGA with a throughput of 1.526 Gbit/sec. The security and efficiency of the hardware speech encryption scheme are validated and the performance is compared with recent works that provided experimental results on Pseudo-Random Number Generation (PRNG) and speech encryption.
2018 IEEE International Conference on Industrial Technology (ICIT)
This paper presents an FPGA design and implementation of a chaotic speech encryption and decrypti... more This paper presents an FPGA design and implementation of a chaotic speech encryption and decryption system based on bit permutations. Different encryption schemes are realized and compared. In addition, various testing methods including entropy, mean squared error, and correlation coefficients are used to analyze the efficiency of the system. The techniques for area and delay minimization are used. Carry look-ahead adder, multi-operand adder and booth multiplier are used to improve the performance of the encryption schemes design. A comparison between the different encryption architectures and the state of the art is introduced. The results demonstrate the good security of the proposed systems, which enables their utilization in speech telecommunication. The designs have been simulated using Xilinx ISE 14.7 and realized on FPGA Xilinx virtex-5 xc5lx50T. A throughput of 7.9 Gbit/sec for bit permutation design, 2.6 Gbit/sec for bit permutation and chaotic modified logistic map is achieved compared with 1.1 Gbit/sec and 1.49 Gbit/sec for previous work.
2016 28th International Conference on Microelectronics (ICM)
Robotic manipulators are currently extensively used in a wide spectrum of industrial, medical and... more Robotic manipulators are currently extensively used in a wide spectrum of industrial, medical and commercial facilities. While it is becoming a trend to use over-actuated manipulators, solution of related inverse kinematics problems becomes more challenging. Recently, more efforts have been directed towards utilizing alternative computationally efficient methods for solving such problems. During the last decade, the use of evolutionary algorithms involving particle swarm optimization as well as neural networks has been on the rise as a plausible alternative. This paper presents a new choice of parameters for the single-objective particle swarm optimization that leads to accurate and computationally efficient solutions. Furthermore, a multi-objective particle swarm optimization technique, which offers more flexibility in the manipulator motion, is introduced. Mathematical formulation of the problem and applications on different robotic manipulators are presented in the paper with good simulation results.
2016 13th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), 2016
To achieve the Shannon's confusion and diffusion properties, an image encryption algorithm sh... more To achieve the Shannon's confusion and diffusion properties, an image encryption algorithm should include permutations and substitutions. This paper presents three different permutation techniques based on discrete chaotic maps. The permutation techniques are, then, evaluated using two measures: the average distance one pixel moved and the average distance between two adjacent pixels. The evaluation is performed for different matrix sizes and considers the scrambling efficiency and the execution time ratios. Furthermore, each of the permutation techniques is used in a simple encryption system and the encrypted images are evaluated using correlation coefficients, differential attack measures, the NIST statistical test suite and sensitivity analysis where promising encryption results are obtained.
Multimedia Tools and Applications
Complexity
This paper proposes a novel generalized switched synchronization scheme amongnfractional-order ch... more This paper proposes a novel generalized switched synchronization scheme amongnfractional-order chaotic systems with various operating modes. Digital dynamic switches and dynamic scaling factors are employed, which offer many new capabilities. Dynamic switches determine the role of each system as a master or a slave. A system can either have a fixed role throughout the simulation time (static switching) or switch its role one or more times (dynamic switching). Dynamic scaling factors are used for each state variable of the master system. Such scaling factors control whether the master is a single system or a combination of several systems. In addition, these factors determine the generalized relation between the original systems from which the master system is built as well as the slave system(s). Moreover, they can be utilized to achieve different kinds of generalized synchronization relations for the purpose of generating new attractor diagrams. The paper presents a mathematical fo...
2016 13th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), 2016
2016 13th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), 2016
In this paper, a generalized scheme for synchronizing a fractional order chaotic system with anot... more In this paper, a generalized scheme for synchronizing a fractional order chaotic system with another one or with a linear combination of two other fractional order chaotic systems is presented. Static (time-independent) or dynamic (time-dependent) synchronization that could generate multiple scaled versions of the response is discussed for some fractional order continuous chaotic systems based on differential equations. Non-Standard finite difference method suitable for fractional order chaotic systems is used to solve each system and get the responses. Analysis in the generalized fractional order case is presented, as well as results of simulations that match the corresponding analysis for different values of fractional order parameters.
A Knowledge-Based Approach to Program Understanding, 1995
IEEE Transactions on Magnetics, 2006
Extensive efforts have been long directed towards the development of shape optimization methodolo... more Extensive efforts have been long directed towards the development of shape optimization methodologies for electromagnetic devices. In case of devices involving nonlinear magnetic media, this optimization process becomes more complicated. This paper demonstrates how shape optimization and field analysis of such devices may be carried out efficiently and conveniently using the particle swarm evolutionary approach and without the involvement of other computational tools. Details of the proposed approach, its application to different electromagnetic devices, and comparisons with finite-element computations are presented in the paper.
IEEE Transactions on Magnetics, 2006
Vector hysteresis models are regarded as helpful tools that can be utilized in the simulation of ... more Vector hysteresis models are regarded as helpful tools that can be utilized in the simulation of multidimensional field-media interactions. Recently, substantial efforts have been focused on the refinement of vector Preisach-type models of hysteresis. The purpose of this paper is to present a computationally efficient vector Preisach-type hysteresis model constructed from only two scalar models having orthogonally interrelated elementary operators. Such a model is implemented via a linear neural network (LNN) fed from the outputs of discrete Hopfield neural network (DHNN) blocks having step activation functions. With this DHNN-LNN configuration, it is possible to carry out the identification process using well-established widely available algorithms. Details of the model, its identification, and experimental testing are presented.
IEEE Transactions on Magnetics, 2010
Accurate evaluation of ambient magnetic low-frequency fields is of great importance to several bi... more Accurate evaluation of ambient magnetic low-frequency fields is of great importance to several biological, noise, and compatibility applications. Due to their low cost, fluxmeters are regarded among the most commonly used devices for those measurement purposes. It is known that a fluxmeter can never resolve local field distributions within its sense coil dimensions. This paper introduces a new wavelet-based approach using which local field values from large sense coil fluxmeter measurements can be inferred. In this approach, wavelets on a bounded interval are used as basis functions for the efficient and accurate solution of the device response integral equation. Details and testing of the approach, in one and two dimensions, are given in the paper. Index Terms-First-kind integral equations, magnetic field measurement, method of moments (MoM), wavelets.
Abstract-This paper presents a knowledge-based analysis approach that generates first order predi... more Abstract-This paper presents a knowledge-based analysis approach that generates first order predicate logic annotations of loops. A classification of loops according to their complexity levels is presented. Based on this taxonomy, variations on the basic analysis approach that best fit each of the different classes are described. In general, mechanical annotation of loops is performed by first decomposing them using data flow analysis. This decomposition encapsulates closely related statements in events, that can be analyzed individually. Specifications of the resulting loop events are then obtained by utilizing patterns, called plans, stored in a knowledge base. Finally, a consistent and rigorous functional abstraction of the whole loop is synthesized from the specifications of its individual events. To test the analysis techniques and to assess their effectiveness, a case study was performed on an existing program of reasonable size. Results concerning the analyzed loops and the p...
Journal of Advanced Research, 2014
Magnetic materials are considered as crucial components for a wide range of products and devices.... more Magnetic materials are considered as crucial components for a wide range of products and devices. Usually, complexity of such materials is defined by their permeability classification and coupling extent to non-magnetic properties. Hence, development of models that could accurately simulate the complex nature of these materials becomes crucial to the multi-dimensional field-media interactions and computations. In the past few decades, artificial neural networks (ANNs) have been utilized in many applications to perform miscellaneous tasks such as identification, approximation, optimization, classification and forecasting. The purpose of this review article is to give an account of the utilization of ANNs in modeling as well as field computation involving complex magnetic materials. Mostly used ANN types in magnetics, advantages of this usage, detailed implementation methodologies as well as numerical examples are given in the paper. ª 2013 Production and hosting by Elsevier B.V. on behalf of Cairo University.
Journal of Advanced Research, 2015
Journal of Magnetism and Magnetic Materials, 2004
This paper presents an automated particle swarm optimization approach using which field computati... more This paper presents an automated particle swarm optimization approach using which field computations may be carried out in devices involving non-linear magnetic media. Among the advantages of the proposed approach are its ability to handle complex geometries and its computational efficiency. The proposed approach has been implemented and computations were carried out for an electromagnet subject to different DC excitation conditions. These computations showed good agreement with the results obtained by the finite-element approach.
Journal of Magnetism and Magnetic Materials, 2003
Magnetostriction models are indispensable to different crucial computational activities such as t... more Magnetostriction models are indispensable to different crucial computational activities such as those dealing with active vibration damping devices and optimum clamping stresses for transformer sheets. This paper presents an efficient magnetostriction Preisach-type model based on the effective field approach. According to this approach, the total applied field may be regarded as a super position of the actual magnetic field and
Journal of Applied Physics, 2000
It has been recently shown that the identification process of scalar, as well as some family of v... more It has been recently shown that the identification process of scalar, as well as some family of vector, Preisach-type models may be accomplished by the aid of artificial neural networks. Our purpose in this article is to further generalize the approach through which neural networks may be utilized for the identification of vector Preisach models, while using arbitrary measured data
IEEE Transactions on Magnetics, 2000
Reluctance motors are currently being used widely in different applications. Sometimes, the rotor... more Reluctance motors are currently being used widely in different applications. Sometimes, the rotor inherent saliency may introduce some difficulty in pursuing an analytical solution to the motor electromagnetic field problem. In this paper, Hopfield artificial neural networks are used to minimize the air-gap magnetic energy function. Thus, a numerical electromagnetic field solution is obtained automatically. Performance of the motor may
IEEE Transactions on Magnetics, 1998
Multimedia Tools and Applications, 2018
This paper proposes a generalized modified chaotic transition map with three independent paramete... more This paper proposes a generalized modified chaotic transition map with three independent parameters. A hardware speech encryption scheme utilizing this map along with a bit permutation network is presented. While the transition map’s generalization introduces additional parameters, the modification enhances its chaotic properties and overcomes the finite range of the control parameter and dynamical degradation problems. The modification also presents a simplification for the hardware realization of the exponentiation operation in the map’s equation because the modified output range allows conversion from the linear domain to the Logarithmic Number System (LNS). Mathematical analysis of the map is presented, where exact nonlinear expressions of the dependent parameters are derived and validated through simulations. To further simplify the hardware realization, the complicated nonlinear expressions are linearized and the introduced approximation error is quite acceptable. The encryption scheme is simulated using Xilinx ISE 14.7 and realized on Xilinx Nexys 4 Artix-7 FPGA with a throughput of 1.526 Gbit/sec. The security and efficiency of the hardware speech encryption scheme are validated and the performance is compared with recent works that provided experimental results on Pseudo-Random Number Generation (PRNG) and speech encryption.
2018 IEEE International Conference on Industrial Technology (ICIT)
This paper presents an FPGA design and implementation of a chaotic speech encryption and decrypti... more This paper presents an FPGA design and implementation of a chaotic speech encryption and decryption system based on bit permutations. Different encryption schemes are realized and compared. In addition, various testing methods including entropy, mean squared error, and correlation coefficients are used to analyze the efficiency of the system. The techniques for area and delay minimization are used. Carry look-ahead adder, multi-operand adder and booth multiplier are used to improve the performance of the encryption schemes design. A comparison between the different encryption architectures and the state of the art is introduced. The results demonstrate the good security of the proposed systems, which enables their utilization in speech telecommunication. The designs have been simulated using Xilinx ISE 14.7 and realized on FPGA Xilinx virtex-5 xc5lx50T. A throughput of 7.9 Gbit/sec for bit permutation design, 2.6 Gbit/sec for bit permutation and chaotic modified logistic map is achieved compared with 1.1 Gbit/sec and 1.49 Gbit/sec for previous work.
2016 28th International Conference on Microelectronics (ICM)
Robotic manipulators are currently extensively used in a wide spectrum of industrial, medical and... more Robotic manipulators are currently extensively used in a wide spectrum of industrial, medical and commercial facilities. While it is becoming a trend to use over-actuated manipulators, solution of related inverse kinematics problems becomes more challenging. Recently, more efforts have been directed towards utilizing alternative computationally efficient methods for solving such problems. During the last decade, the use of evolutionary algorithms involving particle swarm optimization as well as neural networks has been on the rise as a plausible alternative. This paper presents a new choice of parameters for the single-objective particle swarm optimization that leads to accurate and computationally efficient solutions. Furthermore, a multi-objective particle swarm optimization technique, which offers more flexibility in the manipulator motion, is introduced. Mathematical formulation of the problem and applications on different robotic manipulators are presented in the paper with good simulation results.
2016 13th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), 2016
To achieve the Shannon's confusion and diffusion properties, an image encryption algorithm sh... more To achieve the Shannon's confusion and diffusion properties, an image encryption algorithm should include permutations and substitutions. This paper presents three different permutation techniques based on discrete chaotic maps. The permutation techniques are, then, evaluated using two measures: the average distance one pixel moved and the average distance between two adjacent pixels. The evaluation is performed for different matrix sizes and considers the scrambling efficiency and the execution time ratios. Furthermore, each of the permutation techniques is used in a simple encryption system and the encrypted images are evaluated using correlation coefficients, differential attack measures, the NIST statistical test suite and sensitivity analysis where promising encryption results are obtained.
Multimedia Tools and Applications
Complexity
This paper proposes a novel generalized switched synchronization scheme amongnfractional-order ch... more This paper proposes a novel generalized switched synchronization scheme amongnfractional-order chaotic systems with various operating modes. Digital dynamic switches and dynamic scaling factors are employed, which offer many new capabilities. Dynamic switches determine the role of each system as a master or a slave. A system can either have a fixed role throughout the simulation time (static switching) or switch its role one or more times (dynamic switching). Dynamic scaling factors are used for each state variable of the master system. Such scaling factors control whether the master is a single system or a combination of several systems. In addition, these factors determine the generalized relation between the original systems from which the master system is built as well as the slave system(s). Moreover, they can be utilized to achieve different kinds of generalized synchronization relations for the purpose of generating new attractor diagrams. The paper presents a mathematical fo...
2016 13th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), 2016