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Determining the Heavy Metal Pollution in Mascara (Algeria) by Using Casuarina equisetifolia
Lakhdari Aissa
Ecologia Balkanica , 2012,
Abstract: In this study, Casuarina equisetifolia needles were evaluated as the possible biomonitors of heavy metal air pollution in Mascara (Algeria). The needles were sampled from seven locations with different degrees of metal pollution (near roads) and from a control site. The concentrations of lead, zinc, copper and nickel were measured by using a flame atomic absorption spectrophotometer. The maximal values of these four metals were found in the samples collected near the roads and the minimal values were found in the control site. Furthermore, sites with high traffic density and frequency of cars stoppage showed high heavy metal concentrations. However, the comparison of concentrations of all metals showed that the zinc one had the highest concentration of all. The cluster analysis divided the selected sampling sites in three distinct clusters. With regard to the results of this study, Casuarina equisetifolia can be successfully applied in biomonitoring of air pollution.
Nambu-Dirac Structures on Lie Algebroids
Aissa Wade
Mathematics , 2002,
Abstract: The theory of Nambu-Poisson structures on manifolds is extended to the context of Lie algebroids, in a natural way based on the Vinogradov bracket associated with Lie algebroid cohomology. We show that, under certain assumptions, any Nambu-Poisson structure on a Lie algebroid is decomposable.Also, we introduce the concept of a higher order Dirac structure on a Lie algebroid. This allows to describe both Nambu-Poisson structures on Lie algebroids and Dirac structures on manifolds in the same setting.
Optimal M-BCJR Turbo Decoding: The Z-MAP Algorithm  [PDF]
Aissa Ouardi, Ali Djebbari, Boubakar Seddik Bouazza
Wireless Engineering and Technology (WET) , 2011, DOI: 10.4236/wet.2011.24031
Abstract: In this paper, we propose a novel idea for improvement performances of the leader M-BCJR algorithm functioning in low complexity. The basic idea consists to localize error instant possibility, and then increase the complexity around this moment. We also propose an easy and important idea for early localisation of erroneous moments. We call this new algorithm Z-MAP. The simulations show that the improvement of performances is significant. The performances of Z-MAP turbo decoding are so close to full MAP-BCJR performances. Furthermore, the complexity is the same that of the M-BCJR. So, Z-MAP is an optimal version of M-BCJR algorithm.
Biometric Signature of Private Key by Reliable Iris Recognition Based on Flexible-ICA Algorithm  [PDF]
Aissa Boukhari, Salim Chitroub, Imen Bouraoui
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2011, DOI: 10.4236/ijcns.2011.432096
Abstract: The numerical world is under a fast development generating facilities and threats. The recommended solutions are especially the protection of information in all its states. The levels of protection show a discrepancy from an application to another; governmental, commercial or even cybercriminal. The infrastructure used in modern cryptography is based on public key cryptosystem. The problem is how to make safe the private key and to memorize it without difficulties and damages. This paper introduces a biometric solution of owner signature generating an encryption of the key using the iris recognition kept in a smart card. Several precautions were taken to guarantee the safety and the availability of the use of the private key. They are two essential goals to attest: the quality of the service and the robustness of suggested safety. Being the quality of the service, the used iris recognition is based on a new emerging method founded on Flexible-ICA algorithm. This method offers a better Equal Error rate compared to other methods previously used. This quality of recognition was also reinforced by an encoding of error using a flag and finally Reed Solomon encoder. For recommended safety, a scheme based on block encryption is used. The proposed scheme is Propagating Cipher Block chaining which offers a very propagation of a high level of confusion and diffusion. Indeed, the robustness of this cryptographic process was studied by setting up strict criteria of safety.
Filosofia e Educa o na Forma o Contemporanea
Aissa Afonso Guimar?es
Princípios : Revista de Filosofia , 2001,
Abstract:
Secondary Construction of Resilient Functions and Plateaued Functions: Study Their Algebraic Immunity
Belmeguenai Aissa,Doghman Nouredine
Journal of Applied Sciences , 2007,
Abstract: In this study, we first give a survey of the Siegenthaler’s constructions and the general Carlet’s construction of resilient functions, permitting to obtain resilient functions achieving the best possible trade-offs between resiliency order, algebraic degree and nonlinearity. Then, we introduce and we study a new secondary construction of resilient functions based on the principal of the siegenthaler’s construction. This construction permitted to increase the algebraic immunity, algebraic degree and define many more resilient functions where the degree, algebraic immunity, resiliency and nonlinearity achieving are high. Thus, permits to obtain resilient functions achieving the best possible trade-offs between resiliency order, algebraic degree and nonlinearity (that is, achieving Siegenthaler’s and Sarkar, al.’s bounds). We conclude the paper by generalizing our construction to plateaued functions.
Energy decay for wave equations of phi-Laplacian type with weakly nonlinear dissipation
Abbes Benaissa,Aissa Guesmia
Electronic Journal of Differential Equations , 2008,
Abstract: In this paper, first we prove the existence of global solutions in Sobolev spaces for the initial boundary value problem of the wave equation of $phi$-Laplacian with a general dissipation of the form $$ (|u'|^{l-2}u')'-Delta_{phi}u+sigma(t) g(u')=0 quad ext{in } Omega imes mathbb{R}_+ , $$ where $Delta_{phi}=sum_{i=1}^n partial_{x_i}igl(phi (|partial_{x_i}|^2)partial_{x_i}igr)$. Then we prove general stability estimates using multiplier method and general weighted integral inequalities proved by the second author in [18]. Without imposing any growth condition at the origin on $g$ and $phi$, we show that the energy of the system is bounded above by a quantity, depending on $phi$, $sigma$ and $g$, which tends to zero (as time approaches infinity). These estimates allows us to consider large class of functions $g$ and $phi$ with general growth at the origin. We give some examples to illustrate how to derive from our general estimates the polynomial, exponential or logarithmic decay. The results of this paper improve and generalize many existing results in the literature, and generate some interesting open problems.
Grushin problems and control theory: Formulation and examples
Akram Ben Aissa
Mathematics , 2013,
Abstract: In this paper we give a new formulation of an abstract control problem in terms of a Grushin problem, so that we will reformulate all notions of controllability, observability and stability in a new form that gives readers an easy interpretation of these notions.
Weak controllability of second order evolution systems and applications
Akram Ben Aissa
Mathematics , 2013,
Abstract: Controllability and observability are important properties of a distributed paramater systems.The equivalence between the notion of exact observability and exact controllability holds in general. In this work, we define a new notion of controllability say weak which is related to some weak observability inequality and we give the equivalence between.
Multi-Channel Cognitive Radio Networks: Modeling, Analysis and Synthesis
Navid Tadayon,Sonia Aissa
Computer Science , 2014,
Abstract: In this contribution, we establish a model for multichannel cognitive radio networks (CRNs) using the theory of priority queues. This model enables us to conduct a performance analysis in the most general form by the derivation of the probability mass function (PMF) of queue length at the secondary users (SUs). In the second part, a reverse problem is considered to answer the important top-down question of whether a service requirement can be satisfied in a multi-channel CRN knowing the network parameters and traffic situation with respect to the SUs and the primary users (PUs). Terming this problem as the network synthesis, a precise conservation law is obtained, which relates the packet waiting times of both types of users, and based on which the achievable region of the network is also determined. Lastly, by the introduction of a mixed strategy, the conditions for the existence of an optimal trade-off between the interference onto the PUs and the quality-of-service of the SUs is shown, and the optimal mixed strategy is obtained when those conditions are satisfied.
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