Alexandru Serbanescu

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A closed-form state estimator for some polynomial nonlinear systems is derived in this paper. Exploiting full Taylor series expansion we first give exact matrix expressions to compute mean and covariance of any random variable distribution that has been transformed through a polynomial function. An original discrete-time Kalman filtering implementation(More)
—This paper proposes a method to compose and optimize medical services as business workflows. Such a work-flow consists in a set of abstract services, and for each abstract service there are several concrete services. Since each medical service has different QoS (Quality of Service) parameters such as response time, rating, distance and cost, determining(More)
In this article, a new compression method is investigated using a particular chaotic modulation type. The symbolic approach presented associates to every informational sequence a trajectory in the state space of the chaotic generator. We are also introducing a new type of chaotic generator adapted to the probability distribution of the informational(More)
— This paper is devoted to receiver design in a Chaotic Direct-Sequence Spread Spectrum (CD3S) digital communication system. The demodulation is achieved through chaos synchronization in an efficient manner thanks to dual Unscented Kalman Filtering. The problem of carrier phase recovery, frequently neglected in chaos-based communication systems, is(More)
One of the most challenging applications of time-frequency representations deals with the analysis of the signal issued from natural environment. Recently, the interest for passive underwater context increased, basically due to the rich information carried out by the natural signals. Taken into account the non-linear multi-component time-frequency behavior(More)
In this correspondence, we focus on blind estimation of the chip duration of time-hopping signals by introducing a cost function based on time-of-arrival (ToA) folding over multiple observation sets. An optimization algorithm that takes advantage of the highly oscillatory behavior in the nearby of the global minimum is proposed and a performance bound for(More)
The development of the new information security systems based on chaos theory represents a new research field in communication and information technology domain. Cryptography is a permanent field of interest at all times. At present secret communication plays an increasing role in many fields of common life, like banking, industry, and telecommunication. In(More)
In the last decade, the applications of the recurrence plot analysis method make it a valuable alternative to the time-frequency and time-scale tools. As it was initially developed for the study of dynamical systems, and was later used in nonlinear time series analysis, the question of using it as a signal processing tool has not been put into discussion(More)
— This paper adresses the problem of symbol estimation in the case of a spread spectrum based system where the receiver has only the information about the nonlinear function used to generate the spreading sequence. We propose two methods to achieve this, first based on the already considered DUAL form and a correlator second based one. For the DUAL form we(More)