Pedro Julián
Universidad Nacional del Sur
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Pedro Julián.
IEEE Transactions on Circuits and Systems I-regular Papers | 2000
Pedro Julián; A. Desages; B. D'Amico
An inner product is defined for the linear vector space PWL/sub H/[S] of all the piecewise linear (PWL) continuous mappings defined over a rectangular compact set S, using a simplicial partition H. This permits us to assure that PWL/sub H/[S] is a Hilbert space. Then, the notion of orthogonality is introduced and orthonormal bases of PWL functions are formulated. A relevant consequence of the approach is that the problem of function approximation can be translated to the more studied field of approximation in Hilbert spaces of finite dimension. As will be shown, this powerful theoretical framework can be used to generate an optimal scheme for model reduction.
IEEE Transactions on Circuits and Systems I-regular Papers | 2004
Pedro Julián; Andreas G. Andreou; Laurence Riddle; Shihab A. Shamma; David H. Goldberg; Gert Cauwenberghs
Sound localization using energy-aware hardware for sensor networks nodes is a problem with many applications in surveillance and security. In this paper, we evaluate four algorithms for sound localization using signals recorded in a natural environment with an array of commercial off-the-shelf microelectromechanical systems microphones and a specially designed compact acoustic enclosure. We evaluate performance of the algorithms and their hardware complexity which relates directly to energy consumption.
IEEE Transactions on Circuits and Systems I-regular Papers | 1998
Pedro Julián; Mario Jordán; A. Desages
This paper deals with the approximation of smooth functions using canonical piecewise-linear functions. The developing of tools in the field of analysis and control of nonlinear systems based on this kind of functions, as well as its efficiency in the representation of electronic devices, motivates the development of useful methods to obtain accurate approximations. A recursive method is proposed to obtain simultaneously all the parameters required and its convergence is studied. In addition, an iterative method to introduce new partitions on the domain, when the error obtained is not satisfactory, is described. This method takes advantage of the partitions already found to reduce the total number of parameters that the algorithm has to handle.
IEEE Transactions on Circuits and Systems I-regular Papers | 2002
Marco Storace; Pedro Julián; Mauro Parodi
This paper presents a method for the approximate synthesis of nonlinear multiport resistors. According to some fundamental circuit theory results, the general problem of synthesizing a multiport resistor with given constitutive equations corresponds to that of the synthesis of nonlinear controlled sources. Following this idea, in this paper, we focus on the design of nonlinear controlled sources using a piecewise-linear (PWL) approach. The constitutive equations are first approximated by resorting to canonical expressions for continuous PWL functions, and then implemented using a set of elementary building blocks. The proposed method is applied to the synthesis of the nonlinear resistive part of an equivalent circuit of the Hodgkin-Huxley nerve membrane model.
International Journal of Circuit Theory and Applications | 2005
Mauro Parodi; Marco Storace; Pedro Julián
Non-linear multiport resistors are the main ingredients in the synthesis of non-linear circuits. Recently, a particular PWL representation has been proposed as a generic design platform (IEEE Trans. Circuits Syst.-I 2002; 49:1138–1149). In this paper, we present a mixed-signal circuit architecture, based on standard modules, that allows the electronic integration of non-linear multiport resistors using the mentioned PWL structure. The proposed architecture is fully programmable so that the unit can implement any user-defined non-linearity. Moreover, it is modular: an increment in the number of input variables can be accommodated through the addition of an equal number of input modules. Copyright
IEEE Transactions on Circuits and Systems I-regular Papers | 2003
Pedro Julián; Radu Dogaru; Makoto Itoh; Martin Hänggi; Leon O. Chua
Recently, a novel structure called the simplicial cellular neural network (CNN) has been introduced , which permits one to implement any Boolean/Gray-level function of any number of variables. This paper is devoted to explore novel circuit architectures for the implementation of the simplicial CNN based on resonant tunneling diodes. The final objective is to implement a fully programmable CNN in a hardware platform based on nanoelectronic devices.
IEEE Transactions on Circuits and Systems | 2004
Pablo Sergio Mandolesi; Pedro Julián; Andreas G. Andreou
We propose a programmable architecture for a single instruction multiple data image processor that has its foundation on the mathematical framework of a simplicial cellular neural networks. We develop instruction primitives for basic image processing operations and show examples of processing binary and gray scale images. Fabricated in deep submicron CMOS technologies, the complexity of the digital circuits and wiring in each cell is commensurate with pixel level processing.
International Journal of Bifurcation and Chaos | 2001
Makoto Itoh; Pedro Julián; Leon O. Chua
In this paper, we study the relationship between the standard cellular neural network (CNN) and the resonant tunneling diode (RTD)-based CNN. We investigate the functional and advanced capabilities of a new generation of CNNs that exploit the multiplicity of steady states. We also include in the analysis higher order CNNs. Furthermore, some methods for designing RTD-based CNNs with multiple steady states are presented.
ACM Transactions on Sensor Networks | 2006
David H. Goldberg; Andreas G. Andreou; Pedro Julián; Philippe O. Pouliquen; Laurence Riddle; Rich Rosasco
We present a low-power VLSI wake-up detector for a sensor network that uses acoustic signals to localize ground-based vehicles. The detection criterion is the degree of low-frequency periodicity in the acoustic signal, and the periodicity is computed from the “bumpiness” of the autocorrelation of a one-bit version of the signal. We then describe a CMOS ASIC that implements the periodicity estimation algorithm. The ASIC is fully functional and its core consumes 835 nanowatts. It was integrated into an acoustic enclosure and deployed in field tests with synthesized sounds and ground-based vehicles.
international symposium on circuits and systems | 2003
Pedro Julián; Andreas G. Andreou; Pablo Sergio Mandolesi; David H. Goldberg
We present the design and testing of a micropower integrated circuit for the estimation of the bearing angle of a sound source with respect to a pair of microphones. The algorithm is based on a modified binary cross-correlation approach suitable for low-power operation. The circuit has been tested and operates at 600 /spl mu/W at performance levels matching theoretical simulations.