Ghazy M. R. Assassa

A Novel Approach for Hiding Messages in Images

In this paper, a spiral-based Least Significant Bit (LSB) approach for hiding messages in images is presented. The proposed approach is based on the LSB substitution technique applied on RGB color components of BMP images. The key idea is to divide the image into segments and process them differently. The presented approach considers three algorithms corresponding to three spiral substitution. The proposed algorithms are presented and their performance against attacks and processing time are evaluated. The embedding time was compared for the proposed algorithms as function of the message length up to 20 KB. Numerical experimentation suggests that the embedding time varies linearly with the message length. The assessment of the proposed algorithms against attacks was also evaluated using a chi-square analysis technique exhibiting superior performance

On the Development of Electronic Voting: A Survey

Voting is a fundamental decision making instrument in any consensus-based society and democracy depends on the proper administration of popular elections. In any election, there exists a set of requirements among which voters should receive assurance that their intent was correctly captured and that all eligible votes were correctly tallied. On the other hand, the election system as a whole should ensure that voter coercion is unlikely. These conflicting requirements present a significant challenge: how can voters receive enough assurance to trust the election result, but not so much that they can prove to a potential coercer how they voted. The challenge of changing the traditional paper based voting methods used in many developing countries into electronic voting raises a set of functional and constitutional requirements. These requirements are governed by the country in which they operate and are usually not limited to privacy, authentication, fairness, transparency, integrity and incoercibility. This paper presents a survey of electronic voting schemes and systems available to date, classifying them and pointing out advantages and drawbacks of each class. The survey is concluded by presenting a comparative analysis on electronic voting and suggests improvements on some recent e-voting schemes and systems.

Other options of mass and energy input for steam jet refrigeration systems

Abstract A parametric theoretical study is initiated for a solar-powered steam jet refrigeration (SJR) system in order to evaluate to what extent the system par

Computer simulation of the horizontal falling film desalination plant

Abstract In this paper two models are developed; the first one is for the horizontal falling film desalination process and the second one is for a modified combined thermal vapour compression and horizontal falling desalination process. The present models assume a constant heat transfer area in all effects rather than constant temperature drop between the effects. The computed results show that the rate of decrease of the specific heat transfer area of the horizontal falling film process is higher than that of the combined thermal vapour compression and the horizontal falling film processes. After certain maximum allowable operating temperature, depending on the number of effects, the magnitude of the specific heat transfer area of the horizontal falling film process is always smaller than that in the combined thermal vapour compression and the horizontal falling film process. The thermal performance ratio corresponding to the thermal vapour copmpression-horizontal falling film process are much greater than the value corresponding to the horizontal falling film for the same number of effects. The combined thermal vapour compression and the horizontal falling film presented in this paper gives values for the thermal performance ratio higher than the values obtained in the previous conventional combined thermal vapour compression and horizontal falling film desalination process.

Face Recognition Using Incremental Principal Components Analysis

Human face recognition plays a significant role in security applications for access control and real time video surveillance systems, and robotics. Popular approaches for face recognition, such as principal components analysis (PCA), rely on static datasets where training is carried in a batch-mode on a pre-available image set. Real world applications require that the training set be dynamic of evolving nature where within the framework of continuous learning new training images are continuously added to the original set; this would trigger a costly frequent re-computation of the eigen space representation via repeating an entire batch-based training that includes the new images. Incremental PCA methods allow adding new images and updating the PCA representation, and offer the advantage of dispensing with the recently added images after model update. In this paper, various incremental PCA (IPCA) training and relearning strategies are proposed and applied to the candid covariance-free incremental principal component algorithm. The effect of the number of increments and size of the eigen vectors on the correct rate of recognition are studied. The results suggest that batch PCA is inferior to the four considered IPCA1-4, and that all IPCAs are practically equivalent with IPCA3 yielding slightly better results than the other IPCAs.

A Secure Semi-Fragile JPEG Image Authentication Scheme Based on Discrete Cosine Transform

The challenge in the case of image authentication is that in many cases images need to be subjected to non malicious operations like compression, so the authentication techniques need to be compression tolerant. In this paper we propose an image authentication system that remains tolerant to JPEG lossy compression operations. A scheme for JPEG grey scale images is proposed based on a data embedding method that utilizes a secret key and a secret mapping vector in the frequency domain. An encrypted feature vector extracted from the frequency domain, is embedded redundantly, and invisibly in the marked image. On the receiver side, the feature vector from the received image is derived again and compared against the extracted watermark to verify the integrity and authenticity. The proposed scheme is robust against JPEG compression up to a maximum compression of approximately 80%,, but sensitive to malicious attacks such as cutting and pasting. The experimental results demonstrate that the proposed algorithm has the advantages such as simple computation complexity, security, and good robustness to JPEG compression, and efficient detection of tampering, as well as good tolerance to noise.

On the Transformation of Object Oriented-Based Systems to Component-Based Systems

The aim of this paper is to present a framework that allows the generation of component-based software from object-oriented based software. The generation process is achieved via several steps starting from a transformation of the input software codes to their related UML designs; then creating the corresponding graphs whose nodes are elements such as classes and interfaces and the edges are the relationships between those elements. A clustering technique is then used to create a component for each cluster and regenerate the codes accordingly. The framework is a platform-independent and the intermediate outputs are XML-based files. It allows the using of different thresholds to secure a best solution.

Dynamic stability of MSF desalination plants

Abstract In this paper a model is developed which describes the dynamic stability of large multi-stage flash (MSF) desalination plants. In this model, different types of thermodynamic losses in the flashing units and empirical correlations are used in describing the plant characteristics. The differential equations describing the plant are solved with the help of a special computer code. This code can calculate the effect of changing any operating variables on the stability of the plant. Calculated examples are given and compared with the experimental data available.