Books by Jose Manuel Albornoz
El presente documento contiene los Capítulos 1 y 2 de RADIOENLACES DIGITALES, por José Manuel Alb... more El presente documento contiene los Capítulos 1 y 2 de RADIOENLACES DIGITALES, por José Manuel Albornoz. El texto completo se encuentra disponible a través de EDITORIAL ACADÉMICA ESPAÑOLA https://www.eae-publishing.com/ Radioenlaces Digitales José Manuel Albornoz RADIOENLACES DIGITALES JOSÉ M. ALBORNOZ Todos los derechos reservados. c ⃝ José Manuel Albornoz Martos 2007 No está permitida la reproducción total o parcial de este libro, ni su tratamiento informático, ni la transmisión de ninguna forma o por cualquier medio, ya sea electrónico, mecánico, por fotocopia, por registro u otros métodos, sin el permiso previo y por escrito del autor. ii Al espíritu de lucha que mis padres dejaron en mi A mi familia iii iv
O Lord that lends me life, lend me a heart replete with thankfulness. William Shakespeare.
Un breve repaso de las matemáticas de la teoría electromagnética
Papers by Jose Manuel Albornoz
arXiv: Molecular Networks, 2007
A comparison is made between conventional Michaelis-Menten kinetics and two models that take into... more A comparison is made between conventional Michaelis-Menten kinetics and two models that take into account the duration of the conformational changes that take place at the molecular level during the catalytic cycle of a monomer. The models consider the time that elapses from the moment an enzyme-substrate complex forms until the moment a product molecule is released, as well as the recovery time needed to reset the conformational change that took place. In the first model the dynamics is described by a set of delayed differential equations, instead of the ordinary differential equations associated to Michaelis-Menten kinetics. In the second model the delay, the discretization inherent to enzyme reactions and the stochastic binding of substrates to enzimes at the molecular level is considered. All three models agree at equilibrium, as expected; however, out-of-equilibrium dynamics can differ substantially. In particular, both delayed models show oscillations at low values of the Mich...
Stochastically coupled automat Networks are a simple example of a self-organizing system: in this... more Stochastically coupled automat Networks are a simple example of a self-organizing system: in this type of systems under certain conditions spontaneous synchronization can appear. One reason to study spontaneous synchronization is its poten- tial application to the problem of symbol synchronization in digital communication systems. In present work a genetic algo- rithm to optimize the spontaneous synchronous operation in a stochastically coupled Winfree automats network is em- ployed. In the case under study the influences of the possible delays associated with the coupling between elements as well as the noise and interference are neglected..
En este trabajo se estudia el comportamiento de un sistema de generadores de numeros pseudo aleat... more En este trabajo se estudia el comportamiento de un sistema de generadores de numeros pseudo aleatorios (generadores de congruencia lineal, GCLs) en condiciones de acoplamiento mutuo. Se muestra como el acople mutuo mejora las propiedades de estos generadores, haciendolas mas apropiadas para aplicaciones criptograficas. Un algoritmo de cifrado que involucra un sistema de GCLs acoplados es propuesto.
Using a set of heterogeneous competing systems with intra-system cooperation and inter-system unf... more Using a set of heterogeneous competing systems with intra-system cooperation and inter-system unfair competition, we show how the coevolution of the system parameters (degree of cooperation and unfair competition) depends on the external supply of resources. This kind of interaction is found in social, economic, ecological and biochemical systems; as an illustration we consider the competition between drug-selling gangs. The model consists of a set of units (individuals, machines or enzymes) grouped in a number of systems (organizations, factories or glycosomes), each one composed by a fixed number of units that can be organized in three configurations: isolated (monomers), cooperating in couples (dimers), and cooperating in groups of four (tetramers). The units working in cooperating configurations increase their ability to obtain the resources (customers, raw material or substrates). The supply of resources can be polluted by the systems through inhibitors. When an unit absorbs an inhibitor, its function is blocked during a period of time. When the blocked unit belongs to dimers or tetramers, all units in the group are also inhibited to acquire the resource. Two parameters characterize each system: the fraction of monomers and the range of the average production in which the system is allowed to produce inhibitors. By using a genetic algorithm, we observe that the evolution of the parameters of the systems maintains its long term average values for low and high supply rates, but tends to display global evolutive transitions when the supply of raw material lies between abundance and scarcity.
En este trabajo se estudia el comportamiento de un sistema de generadores de números pseudo aleat... more En este trabajo se estudia el comportamiento de un sistema de generadores de números pseudo aleatorios (generadores de congruencia lineal, GCLs) en condiciones de acoplamiento mutuo. Se muestra cómo el acople mutuo mejora las propiedades de estos generadores, haciéndolas más apropiadas para aplicaciones criptográficas. Un algoritmo de cifrado que involucra un sistema de GCLs acoplados es propuesto.
El presente documento contiene los Capítulos 1 y 2 de RADIOENLACES DIGITALES, por José Manuel Alb... more El presente documento contiene los Capítulos 1 y 2 de RADIOENLACES DIGITALES, por José Manuel Albornoz. El texto completo se encuentra disponible a través de EDITORIAL ACADÉMICA ESPAÑOLA https://www.eae-publishing.com/ Radioenlaces Digitales José Manuel Albornoz RADIOENLACES DIGITALES JOSÉ M. ALBORNOZ Todos los derechos reservados. c ⃝ José Manuel Albornoz Martos 2007 No está permitida la reproducción total o parcial de este libro, ni su tratamiento informático, ni la transmisión de ninguna forma o por cualquier medio, ya sea electrónico, mecánico, por fotocopia, por registro u otros métodos, sin el permiso previo y por escrito del autor. ii Al espíritu de lucha que mis padres dejaron en mi A mi familia iii iv
The development of wideband mobile communications systems require a better knowledge of the chara... more The development of wideband mobile communications systems require a better knowledge of the characteristics of the mobile channel as described by its impulse response. Such impulse response can be modelled as a tapped delay line with unknown delays, amplitudes and phases associated with each tap. In order to obtain satisfactory estimates of these parameters a wideband channel sounder is required. In this thesis we examine the factors that determine the performance of such a system and develop a channel estimation algorithm that provides multipath resolution capabilities that are significantly better than the reciprocal of the transmission bandwidth.
Using a set of heterogeneous competing systems with intra-system cooperation and inter-system unf... more Using a set of heterogeneous competing systems with intra-system cooperation and inter-system unfair competition, we show how the co- evolution of the system parameters (degree of cooperation and unfair competition) depends on the external supply of resources. This kind of interaction is found in social, economic, ecological and biochemi- cal systems; as an illustration we consider the competition between drug-selling
The development of wideband mobile communications systems require a better knowledge of the chara... more The development of wideband mobile communications systems require a better knowledge of the characteristics of the mobile channel as described by its impulse response. Such impulse response can be modelled as a tapped delay line with unknown delays, amplitudes and phases associated with each tap. In order to obtain satisfactory estimates of these parameters a wideband channel sounder is required. In this thesis we examine the factors that determine the performance of such a system and develop a channel estimation algorithm that provides multipath resolution capabilities that are significantly better than the reciprocal of the transmission bandwidth.
Using a set of heterogeneous competing systems with intra-system cooperation and inter-system unf... more Using a set of heterogeneous competing systems with intra-system cooperation and inter-system unfair competition, we show how the co- evolution of the system parameters (degree of cooperation and unfair competition) depends on the external supply of resources. This kind of interaction is found in social, economic, ecological and biochemi- cal systems; as an illustration we consider the competition between drug-selling
The development of wideband mobile communications systems require a better knowledge of the chara... more The development of wideband mobile communications systems require a better knowledge of the characteristics of the mobile channel as described by its impulse response. Such impulse response can be modelled as a tapped delay line with unknown delays, amplitudes and phases associated with each tap. In order to obtain satisfactory estimates of these parameters a wideband channel sounder is required. In this thesis we examine the factors that determine the performance of such a system and develop a channel estimation algorithm that provides multipath resolution capabilities that are significantly better than the reciprocal of the transmission bandwidth.
The European Physical Journal B, 2010
Using a set of heterogeneous competing systems with intra-system cooperation and inter-system agg... more Using a set of heterogeneous competing systems with intra-system cooperation and inter-system aggression, we show how the coevolution of the system parameters (degree of organization and conditions for aggression) depends on the rate of supply of resourcesṠ. The model consists of a number of units grouped into systems that compete for the resource S; within each system several units can be aggregated into cooperative arrangements whose size is a measure of the degree of organization in the system. Aggression takes place when the systems release inhibitors that impair the performance of other systems. Using a mean field approximation we show that i) even in the case of identical systems there are stable inhomogeneous solutions, ii) a system steadily producing inhibitors needs large perturbations to leave this regime, and iii) aggression may give comparative advantages. A discrete model is used in order to examine how the particular configuration of the units within a system determines its performance in the presence of aggression. We find that full-scale, one sided aggression is only profitable for less-organized systems, and that systems with a mixture of degrees of organization exhibit robustness against aggression. By using a genetic algorithm we find that, in terms of the full-occupation resource supply rateṠF , the coevolution of the set of systems displays the following behavior: i) forṠ <ṠF /10 aggressions are irrelevant and most systems exhibit a high degree of organization; ii) ForṠF /10 <Ṡ <ṠF /3 aggressions are frequent, making systems with a low degree of organization competitive; iii) forṠF /3 <Ṡ <ṠF /2 the systems display global evolutive transitions between periods of calm (few aggressions and high degree of organization) and periods of belligerence (frequent aggressions and low degree of organization); iv) forṠ >ṠF /2 the periods of aggression becomes progressively rarer and shorter. Finally, whenṠ approachesṠF the selection pressure on the cooperativity and the aggression between systems disappears. This kind of model can be useful to analyse the interplay of the cooperation/competition processes that can be found in some social, economic, ecological and biochemical systems; as an illustration we refer to the competition between drug-selling gangs.
This document provides a brief review on the state of the art of data centre simulation. Energy, ... more This document provides a brief review on the state of the art of data centre simulation. Energy, airflow, hybrid and other types of simulation are described, as well as their advantages and limitations. Examples of each type of simulation tool are also mentioned.
A Matlab code to calculate the specific enthalpy of a flow of cooled moist air is presented. The ... more A Matlab code to calculate the specific enthalpy of a flow of cooled moist air is presented. The code is equivalent to a Mollier diagram, allowing the user to calculate relative humidity (or specific humidity) and specific enthalpy of air after a heat exchanger or another similar device has been used to cool it. The output of the code can be used to determine the heat power that a cooling unit must remove to cool air to a certain temperature, making it useful in data centre design and in the control of an air conditioning system.
The energy efficiency of two in-rack cooling configurations is determined analytically using data... more The energy efficiency of two in-rack cooling configurations is determined analytically using data from the Atsugi experimental data centre: one where the cooling unit is placed before the servers inlets, and another where the cooling unit is placed after the servers exhausts. An analysis in terms of the energy efficiency ratio that can be achieved by both configurations was performed in two cases: one where the power required by the chilled water pump and fans is fixed, and another where this power changes in response to changes in the temperature of the air that enters the cooling unit. The results indicate that placing the cooling unit after the rack results in optimum energy efficiency for a certain range of server exhaust temperatures.
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Books by Jose Manuel Albornoz
Papers by Jose Manuel Albornoz