Ahmad A. Mohammad

An improved SVD-based watermarking scheme for protecting rightful ownership

In this paper, a new SVD-based digital watermarking scheme for ownership protection is proposed. The proposed algorithm solves the problem of false-positive detection. In addition, it enjoys all the advantages of SVD-based schemes. Instead of using a randomly generated Gaussian sequence, a meaningful text message is used. Thus, clarity of the extracted message determines the performance of the algorithm. Analytical and experimental developments show that the proposed algorithm is robust and secure. Comparisons with other algorithms indicate that the proposed algorithm is robust against most common attacks. In particular, the algorithm proved to be extremely robust against geometrical distortion attacks.

A new digital image watermarking scheme based on Schur decomposition

In this paper, we present a new digital watermarking scheme for ownership protection. The algorithm embeds the watermark in the Schur decomposition components of the cover image. We also show that this algorithm is noninvertible. Comparisons with other algorithms indicate that the proposed algorithm is robust against most common attacks including geometrical distortions and jpeg compression attacks. Simulations show that the performance of this algorithm outperforms the closely related singular value decomposition based algorithms. More specifically, the proposed algorithm is more robust and requires less number of computations. In addition, our algorithm does not suffer the false positive detection problem inherent in SVD based algorithms.

Hybrid DWT-SVD audio watermarking

Audio watermarking is a relatively new technology that aims to embed copyright information in audio signals as a proof of their ownership. The driving force behind this technology has been the ever-increasing illegal manipulation of genuine audio products released by the music industry. In this paper, we propose an effective, robust, and inaudible audio watermarking algorithm. The effectiveness of algorithm has been brought by virtue of applying a cascade of two powerful mathematical transforms; the discrete wavelets transform (DWT) and the singular value decomposition (SVD). Reported experimental results demonstrate the effectiveness of the proposed algorithm.

Crypto-Watermarking of Transmitted Medical Images.

Telemedicine is a booming healthcare practice that has facilitated the exchange of medical data and expertise between healthcare entities. However, the widespread use of telemedicine applications requires a secured scheme to guarantee confidentiality and verify authenticity and integrity of exchanged medical data. In this paper, we describe a region-based, crypto-watermarking algorithm capable of providing confidentiality, authenticity, and integrity for medical images of different modalities. The proposed algorithm provides authenticity by embedding robust watermarks in images’ region of non-interest using SVD in the DWT domain. Integrity is provided in two levels: strict integrity implemented by a cryptographic hash watermark, and content-based integrity implemented by a symmetric encryption-based tamper localization scheme. Confidentiality is achieved as a byproduct of hiding patient’s data in the image. Performance of the algorithm was evaluated with respect to imperceptibility, robustness, capacity, and tamper localization, using different medical images. The results showed the effectiveness of the algorithm in providing security for telemedicine applications.

Audio watermarking using wavelets

Copyright right protection of digital multimedia has been receiving considerable attention in the last decade. Many effective watermarking algorithms have been proposed and implemented for digital images and digital video, however, few algorithms have been proposed for audio watermarking. This is due to the fact that the human audio system (HAS) is far more complex and sensitive than the human visual system (HVS). In this paper, we describe an imperceptible and robust audio watermarking algorithm based on the discrete wavelet transform (DWT). Performance of the algorithm has been evaluated extensively, and simulation results demonstrate the imperceptibility (inaudibility) and robustness of the proposed algorithm.

A transformation approach for model order reduction of nonlinear systems

A novel technique for nonlinear model order reduction is developed. A transformation matrix is devised from a representative model of the original nonlinear system and applied to the nonlinear model to provide a reduced-order nonlinear model. Linearization is not necessary. Most methods used to compute the transformation matrix for linear system model reduction, such as balancing and aggregation, can be used. In certain situations, the linear system obtained by linearizing the nonlinear system about its equilibrium point can be used as the representative model. To illustrate the proposed procedure, a numerical example is included.<<ETX>>

A new optimal root locus technique for LQR design

In this paper, a new optimal root locus technique is presented. It relies on the choice of the performance index in the linear quadratic regulator (LQR) problem. The choice of the states weighting matrix Q is made so that the solution of the resulting algebraic Riccati equation (ARE) is known in advance. This eliminates the need to solve the (2n x 2n) eigenvalue/eigenvector problem usually needed to solve the ARE. With this choice of Q, the solution of the ARE becomes a constant multiple of the observability Gramian. The control law is easily calculated in O(n2) flops. This is a good improvement over the Chang-Letov method, which in general requires O(2n)3 flops. The weighting matrix Q, the feedback control gain K, and the cost J are directly given as functions of the observability Gramian. Although the algorithm is given for any coordinate system, the development in balanced coordinates is particularly interesting. In this coordinate system, Q, K, and J are directly given as functions of the observability and controllability Gramians and the Hankel singular values of the system. Finally, it is shown that the optimal root locus can be obtained using ordinary root locus and develops efficient rules and algorithms.

On the simulation of the Space Shuttle main engine

The Space Shuttle main engine simulation is analyzed to determine the means to obtain a faster running simulation. In particular, the valve dynamics module is simulated using three different techniques: Eulers method, Adams-Bashforth two-step method, and the matrix stability region placement two-step method. It is shown that, by choosing the integration method appropriately, a speed-up factor of about five can be achieved. The valve dynamics module simulation results are then used to make recommendations about the simulation of the Space Shuttle main engine.<<ETX>>