Sellami Ali

Comparison of the effect structure on Ring and Linear Cavity Lasers of Er-Doped Optical Fibers

Two erbium doped fiber laser configurations are conceived and constructed; A ring fiber laser and a linear cavity fiber loop laser. A comparative investigation tests were carried out. It is found that both the output power and the side mode suppression ratio (SMSR) for the two structures were significantly different. The measured laser power and the side mode suppression ratio (SMSR) of 11 mW and 75 dB respectively were higher for the linear cavity configuration. A lower output power and SMSR of 3 mW and 61.5 dB respectively were obtained with the ring laser configuration. Both lasers were pumped with a 90 mW pump power, and had a reflectivity of 90%.

A Novel Erbium-Doped Fiber Laser source (EDFL)

A novel configuration of a new erbium doped fiber laser (EDFL) is constructed and analyzed. It utilizes embedded fiber-loop mirrors, tunable filters with a linear laser oscillation. Implementing the linear cavity fiber loop (LCFL) as a new configuration using three circulators and two tunable band-pass filters (TBF), the output power in the single wavelength (SW) laser was improved. The output power of the proposed laser system is more than 18 dBm at 1560 nm. The side mode suppression ratio (SMSR) in the output power in this experiment was also high, greater than 64 dB. It is found that the double filtering technique in the proposed configuration enables the system to achieve higher power and lower amplified spontaneous emission (ASE) noise levels.

Multicast network security using quantum key distribution (QKD)

We reviewed the confidentiality and authentication for multi-party applications. A conceptual model of a secure multicast network has been presented by adding a quantum key distribution (QKD) network to its architecture. The model is divided into three phases, the first phase, QKD network generate secure keys to encrypt not only data but also authentication process. The second phase, authentication making sure that no one except the legitimate user receive the message and making sure that nobody except the legitimate sender writes or modifies it. In the last phase, Multicast network encrypt the data by secure key and send it to receivers. The proposed scheme amid to provide a secure end to end communication for multicast network.

How to model wireless mesh networks topology

The specification of network connectivity model or topology is the beginning of design and analysis in Computer Network researches. Wireless Mesh Networks is an autonomic network that is dynamically self-organised, self-configured while the mesh nodes establish automatic connectivity with the adjacent nodes in the relay network of wireless backbone routers. Researches in Wireless Mesh Networks range from node deployment to internetworking issues with sensor, Internet and cellular networks. These researches require modelling of relationships and interactions among nodes including technical characteristics of the links while satisfying the architectural requirements of the physical network. However, the existing topology generators model geographic topologies which constitute different architectures, thus may not be suitable in Wireless Mesh Networks scenarios. The existing methods of topology generation are explored, analysed and parameters for their characterisation are identified. Furthermore, an algorithm for the design of Wireless Mesh Networks topology based on square grid model is proposed in this paper. The performance of the topology generated is also evaluated. This research is particularly important in the generation of a close-to-real topology for ensuring relevance of design to the intended network and validity of results obtained in Wireless Mesh Networks researches.

A new application of multistage homotopy perturbation method to the chaotic Rössler system

In this paper, we present a numerical scheme based on an adaptation of the standard homotopy-perturbation method (HPM) is applied to the Chaotic Rossler system. The standard HPM is converted into a hybrid numeric-analytic method called the multistage HPM (MHPM). Comparisons with the fourth-order Runge-Kutta method (RK4) and standard HPM show that the MHPM is a reliable method for nonlinear equations.

Controlling power output of solar chimney power plant according to demand

ABSTRACT The solar chimney power plant (SCPP) is a simple solar thermal power plant that is capable of converting solar energy into thermal energy in the solar collector. In the second stage, the generated thermal energy is converted into kinetic energy in the chimney and ultimately into electric energy using a combination of a wind turbine and a generator. The numerical simulations were performed for the geometry of the prototype in Manzanares, Spain. Using computational fluid dynamics (CFD) techniques; we have simulated a two-dimensional axisymmetric model of a SCPP with the RNG k-ε turbulence. In this model, the discrete ordinates (DO) radiation model was implemented to solve the radiative transfer equation, using a two-band radiation model. The main objective of this work is to explore dynamic control over plant power output. We have presented a technique to control the power output of the solar chimney power plant, in order to deliver power according to specified demand patterns. In order to present this, the reference plant model was modified to include a secondary and tertiary collector roof under the existing main collector. In terms of base load electricity generation, the inclusion of a secondary and tertiary collector roof produces good control over plant output.

Implementation of SARG04 decoy state quantum key distribution

The experiment of decoy state QKD has been reported using commercial QKD system based on a standard bi-directional ‘Plug & Play’ set-up. By making simple modifications to a commercial quantum key distribution system, decoy state QKD allows us to achieve much better performance than QKD system without decoy state in terms of key generation rate and distance. One decoy state protocol has been implemented. The obtained results demonstrate an unconditionally secure key rate of 0.127 × 10–4 per pulse for a 10 km fiber length.