OALib Journal期刊

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2017 ( 8 )

2016 ( 46 )

2015 ( 129 )

2014 ( 194 )


匹配条件: “Omar Khadir” ,找到相关结果约4264条。
Algorithm for factoring some RSA and Rabin moduli
Omar Khadir
Computer Science , 2013,
Abstract: In this paper we present a new efficient algorithm for factoring the RSA and the Rabin moduli in the particular case when the difference between their two prime factors is bounded. As an extension, we also give some theoretical results on factoring integers.
Insecure primitive elements in an ElGamal signature protocol
Omar Khadir
Computer Science , 2015,
Abstract: Consider the classical ElGamal digital signature scheme based on the modular relation $\alpha^m\equiv y^r\, r^s\ [p]$. In this work, we prove that if we can compute a natural integer $i$ such that $\alpha^i\ mod\ p$ is smooth and divides $p-1$, then it is possible to sign any given document without knowing the secret key. Therefore we extend and reinforce Bleichenbacher's attack presented at Eurocrypt'96.
New variant of ElGamal signature scheme
Omar Khadir
Computer Science , 2013,
Abstract: In this paper, a new variant of ElGamal signature scheme is presented and its security analyzed. We also give, for its theoretical interest, a general form of the signature equation.
Conditions on the generator for forging ElGamal signature
Omar Khadir
Computer Science , 2013,
Abstract: This paper describes new conditions on parameters selection that lead to an efficient algorithm for forging ElGamal digital signature. Our work is inspired by Bleichenbacher's ideas.
A Special Integer Sequence Strongly Connected to the Discrete Logarithm Problem
Omar Khadir,Laszlo Szalay
Journal of Theoretical Physics and Cryptography , 2013,
Abstract: Let p be a large prime integer. In this work, we study the recurrent sequence defined by ... and ... . This integer sequence has connection with the discrete logarithm problem, and under certain assumptions, we obtain an exact solution.
New digital signature protocol based on elliptic curves
Ounasser Abid,Jaouad Ettanfouhi,Omar Khadir
Computer Science , 2013,
Abstract: In this work, a new digital signature based on elliptic curves is presented. We established its efficiency and security. The method, derived from a variant of ElGamal signature scheme, can be seen as a secure alternative protocol if known systems are completely broken.
A Study on Teaching Effectiveness of Self-Financing Engineering College Teachers in Kerala
R. Renjith Kumar,Fezeena Khadir
International Journal of Asian Social Science , 2013,
Abstract: The process of evaluating the effectiveness of teachers has changed over time along with the definition of what effective teaching is due to the increasing attention by the management of self-financing institutes. This research examines to measure the various attributes of teaching effectiveness. The objective of this study is to evaluate the level of teaching effectiveness attributes and to find out the attribute that most contributes to teaching effectiveness. A sample of 96 teachers from an engineering college in Ernakulam, Kerala State, India is taken for the study. The study revealed that there is a lack of team effort, teaching efficiency, and class room behavior. The teaching effectiveness of the engineering teachers is proved to be medium. The study highlights those teaching attributes to be enhanced and suggestive measures are also mentioned to improve the performance of teachers and thereby increase the quality of education and students.
Bending Analysis of Symmetrically Laminated Plates
Leonardo Journal of Sciences , 2010,
Abstract: In the classical plate theory, it is assumed that the plane cross sections initially normal to the plate midsurface before deformation remain plane and normal to that surface during deformation. This is the result of neglecting the transverse shear strains. However, in thick and moderately thick laminated plates, significant transverse shear strains occur, and the theory gives inaccurate results for the plates. So, it is obvious that the shear strains have to be taken into account. There are numerous theories of plates and laminated plates that include the transverse shear strains. One of them is the Reissner and Midlin theory , known as the first-order shear deformation theory, which defines the displacement field as linear variations of midplane displacements. This theory, where the relation between the resultant shear forces and the shear strains is obtained by using shear correction factors, has some advantages due to its simplicity and low computational cost. Some other plate theories, namely the higher-order shear deformation theories, include the effect of transverse shear strains . For example, the theory developed by Reddy allows not only for the transverse shear strains, but also for parabolic variations in the strains across the plate thickness, and thus there is no need to use shear correction coefficients in computing the shear stresses. The present stud is a survey of plate bending of cross-ply laminate by using the finite element method (F.E.M). Using ANSYS, the most known software in the domain for it, two types of modeling are proposed: the first is modeling using a type of shell element, Shell 99 and the second is an approach based on a of type solid element, Solid 46. The results obtained are compared with the results of the theory of Reddy.
Hard Decision-Based PWM for MIMO-OFDM Radar  [PDF]
Omar Daoud
Communications and Network (CN) , 2015, DOI: 10.4236/cn.2015.71004
Abstract: For the purpose of target localization, Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) radar has been proposed. OFDM technique has been adopted in order to a simultaneous transmission and reception of a set of multiple narrowband orthogonal signals at orthogonal frequencies. Although multi-carrier systems such as OFDM support high data rate applications, they do not only require linear amplification but also they complicate the power amplifiers design and increase power consumption. This is because of high peak-to-average power ratio (PAPR). In this work, a new proposition has been made based on the Pulse Width Modulation (PWM) to enhance the MIMO-OFDM radar systems’ performance. In order to check the proposed systems performance and its validity, a numerical analysis and a MATLAB simulation have been conducted. Nevertheless of the system characteristics and under same bandwidth occupancy and system’s specifications, the simulation results show that this work can reduce the PAPR values clearly and show capable results over the ones in the literature.
Numerical Investigation of Phase and Group Propagation of Time-Domain Signals in a Novel Band-Reject Metamaterial Ring Hybrid  [PDF]
Omar Siddiqui
Journal of Computer and Communications (JCC) , 2015, DOI: 10.4236/jcc.2015.36002
Abstract: Phase and group propagation in metamaterial-based microwave components has always been intellectually challenging for students and engineers new to the area of periodic structures and metamaterials. This paper aims in tackling this important topic by studying the wave propagation in a metamaterial-based microwave device. Hence, the contribution of this paper is twofold. First, design of a novel metamaterial ring hybrid (or rate-race) is presented which has a large rejection band so that the second and third harmonics are effectively suppressed. Second, the electromagnetic phase and the group propagation in the ring hybrid are investigated by numerically exciting the input ports with band-limited Gaussian pulses and then finding their responses at various locations in the device.

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