Information-theoretic analysis of a family of additive energy channels

This dissertation studies a new family of channel models for non-coherent com- munications, the additive energy channels. By construction, the additive en- ergy channels occupy an intermediate region between two widely used channel models: the discrete-time Gaussian channel, used to represent coherent com- munication systems operating at radio and microwave frequencies, and the discrete-time Poisson channel, which often appears in the analysis of intensity- modulated systems working at optical frequencies. The additive energy chan- nels share with the Gaussian channel the additivity between a useful signal and a noise component. However, the signal and noise components are not complex- valued quadrature amplitudes but, as in the Poisson channel, non-negative real numbers, the energy or squared modulus of the complex amplitude. The additive energy channels come in two variants, depending on whether the channel output is discrete or continuous. In the former case, the energy is a multiple of a fundamental unit, the quantum of energy, whereas in the second the value of the energy can take on any non-negative real number. For con- tinuous output the additive noise has an exponential density, as for the energy of a sample of complex Gaussian noise. For discrete, or quantized, energy the signal component is randomly distributed according to a Poisson distribution whose mean is the signal energy of the corresponding Gaussian channel; part of the total noise at the channel output is thus a signal-dependent, Poisson noise component. Moreover, the additive noise has a geometric distribution, the discrete counterpart of the exponential density. Contrary to the common engineering wisdom that not using the quadrature amplitude incurs in a signi¯cant performance penalty, it is shown in this dis- sertation that the capacity of the additive energy channels essentially coincides with that of a coherent Gaussian model under a broad set of circumstances. Moreover, common modulation and coding techniques for the Gaussian chan- nel often admit a natural extension to the additive energy channels, and their performance frequently parallels those of the Gaussian channel methods. Four information-theoretic quantities, covering both theoretical and practi- cal aspects of the reliable transmission of information, are studied: the channel capacity, the minimum energy per bit, the constrained capacity when a given digital modulation format is used, and the pairwise error probability. Of these quantities, the channel capacity sets a fundamental limit on the transmission capabilities of the channel but is sometimes di±cult to determine. The min- imum energy per bit (or its inverse, the capacity per unit cost), on the other hand, turns out to be easier to determine, and may be used to analyze the performance of systems operating at low levels of signal energy. Closer to a practical ¯gure of merit is the constrained capacity, which estimates the largest amount of information which can be transmitted by using a speci¯c digital modulation format. Its study is complemented by the computation of the pairwise error probability, an e®ective tool to estimate the performance of practical coded communication systems. Regarding the channel capacity, the capacity of the continuous additive energy channel is found to coincide with that of a Gaussian channel with iden- tical signal-to-noise ratio. Also, an upper bound |the tightest known| to the capacity of the discrete-time Poisson channel is derived. The capacity of the quantized additive energy channel is shown to have two distinct functional forms: if additive noise is dominant, the capacity is close to that of the continu- ous channel with the same energy and noise levels; when Poisson noise prevails, the capacity is similar to that of a discrete-time Poisson channel, with no ad- ditive noise. An analogy with radiation channels of an arbitrary frequency, for which the quanta of energy are photons, is presented. Additive noise is found to be dominant when frequency is low and, simultaneously, the signal-to-noise ratio lies below a threshold; the value of this threshold is well approximated by the expected number of quanta of additive noise. As for the minimum energy per nat (1 nat is log2 e bits, or about 1.4427 bits), it equals the average energy of the additive noise component for all the stud- ied channel models. A similar result was previously known to hold for two particular cases, namely the discrete-time Gaussian and Poisson channels. An extension of digital modulation methods from the Gaussian channels to the additive energy channel is presented, and their constrained capacity determined. Special attention is paid to their asymptotic form of the capacity at low and high levels of signal energy. In contrast to the behaviour in the vi Gaussian channel, arbitrary modulation formats do not achieve the minimum energy per bit at low signal energy. Analytic expressions for the constrained capacity at low signal energy levels are provided. In the high-energy limit simple pulse-energy modulations, which achieve a larger constrained capacity than their counterparts for the Gaussian channel, are presented. As a ¯nal element, the error probability of binary channel codes in the ad- ditive energy channels is studied by analyzing the pairwise error probability, the probability of wrong decision between two alternative binary codewords. Saddlepoint approximations to the pairwise error probability are given, both for binary modulation and for bit-interleaved coded modulation, a simple and e±cient method to use binary codes with non-binary modulations. The meth- ods yield new simple approximations to the error probability in the fading Gaussian channel. The error rates in the continuous additive energy channel are close to those of coherent transmission at identical signal-to-noise ratio. Constellations minimizing the pairwise error probability in the additive energy channels are presented, and their form compared to that of the constellations which maximize the constrained capacity at high signal energy levels

Technology roadmapping in security and defence foresight

Purpose: This paper aims to provide an analysis of Spanish Defence National Foresight Exercise. Design/methodology/approach: The analysis is based on a content analysis of public domain Spanish Defence National Foresight Exercise, and a study directed to analyse the impact on defence technological and industrial base. Findings: Foresight studies on the defence and security environment uses hybrid methodologies, but rarely involve all the stakeholders, and specially the citizens. The authors place a particular emphasis on the impact of these defence and security foresight studies, and following policies to increase the competitiveness and advanced technologies in the future. The analysis of the Spanish contractors allows an evaluation of the roadmaps as a policy instrument for the industrial defence industry. The main challenges for the next exercises in the European countries are to increase the interest in the firms' intelligence systems, and the participation and representation of citizens as a way to guarantee their rights. Therefore, a technology roadmap must be complemented with other more participative foresight methods. Originality/value: Foresight studies on the defence and security environment have been the subject of very few systematic analyses of impact. This paper makes a contribution to such analysis

Surface energy budget at Curiosity through observations and column modeling

Diurnal ground surface temperatures (T-g) and the five major terms of the surface energy budget (SEB) are dis-played from hourly Mars Science Laboratory observations and from column model simulations in four contrasting cases along the Curiosity traverse. T(g )and the SEB terms are otherwise well simulated on regolith near the landing spot and on rocky Pahrump Hills, but the residual in observation-based SEB (-downwelling longwave radiation) shows unexplained peaks in the morning and evening and simultaneously model-T(g )is too cold. Enhanced or diurnally variable crater dust does not help but diurnally variable soil thermal inertia (suggested by Fourier analysis of observed T-g) reduces both defects at both sites. Sand on the steep Namib dune is instead homogeneous, defects here being reduced by taking into account slope effects. Regolith at the 2018 dust storm site appears inhomogeneous, with the SEB terms and T(g )relatively well simulated even in this case of extremely heavy dust load.Peer reviewe

Inner-Hair Cells Parameterized-Hardware Implementation for Personalized Auditory Nerve Stimulation

In this paper the hardware implementation of an inner hair cell model is presented. Main features of the design are the use of Meddis’ transduction structure and the methodology for Design with Reusability. Which allows future migration to new hardware and design refinements for speech processing and custom-made hearing aid

Recent Developments in Chiral Unitary Dynamics of Resonances

In this talk I summarize recent findings made on the description of axial vector mesons as dynamically generated states from the interaction of peseudoscalar mesons and vector mesons, dedicating some attention to the two $K_1(1270)$ states. Then I review the generation of open and hidden charm scalar and axial states. Finally, I present recent results showing that the low lying $1/2^+$ baryon resonances for S=-1 can be obtained as bound states or resonances of two mesons and one baryon in coupled channels dynamics.Comment: Talk at the International Conference on Hadron Physics, Troia07, Canakkale, Turkey, Sep. 2007 and at the Chiral Symmetry in Hadron and Nuclear Physics Workshop, Chiral07, Osaka, November 200

Retrograded mylonitic granulites and phyllonite formation in Azul megashear zone, Tandilia

En el sector norte del Cerro Negro, ubicado en el extremo occidental de la Megacizalla de Azul (MCA), Sierras Septentrionales de la Provincia de Buenos Aires, se destaca la presencia de una faja de filonitas de dirección este-oeste, asociada a granulitas deformadas y retrogradadas, mostrando la gradación completa entre protomilonitas y ultramilonitas. Las filonitas presentan una intensa biotitización de los anfíboles y piroxenos de las rocas originales, y en menor proporción, formación de mica blanca a partir de los feldespatos. Los estudios microtectónicos y la presencia de varios períodos de pseudotaquilización indican que las rocas miloníticas de alto grado características de este sector de la MCA habrían sufrido un cizallamiento posterior, en condiciones dúctil-frágiles acompañado de una removilización de fluidos que originó la retrogradación de las rocas originales, y la consecuente formación de filonitas.At the western end of the Azul megashear zone, which is part of the Sierras Septentrionales of Buenos Aires, an east-west belt of phyllonites occur on the north side of the cerro Negro.These outcrops of phyllonites are associated with deformed and retrogra- ded granulites, showing a complete gradation between protomylonites and ultramylonites. An intense biotitization of amphibo- le and pyroxene of the original rocks becomes dominant, as well as the formation of white mica from feldspar, though in a lesser extent. Microtectonic studies and the identification of several periods of pseudotachylyzation indicate that high grade mylonitic rocks of the Azul megashear zone have undergone subsequent shear deformation under ductile-brittle conditions, accompanied by a remobilization of fluids that caused the retrogression of the original rocks, and the phyllonite formation.Fil: Frisicale, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Angeletti, Melisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Dimieri, Luis Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Martinez, Juan Cruz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Dristas, Jorge A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; Argentin

Use of Native Grassland in Small-Scale Dairy Systems in the Highlands of Central Mexico. A Case Study

Small-scale dairy systems in Mexico comprise 78% of specialized dairy farms and provide 37% of national production. They are small farms with herds 3-35 cows plus replacements, and rely on family labour (Posadas-Domínguez et al., 2014). In the highlands, many farms have native grasslands, grazed during the rainy season, and supplemented with other feeds as maize straw, maize grain and maize ears. Native grasslands have not been studied in this context. This is a case study on the use of native grassland in a small-scale dairy farm. The objective was to determine how native grasslands are integrated in feeding milking dairy cows, and the feeding costs involved

Baryon Resonances

In this talk I show recent results on how many excited baryon resonances appear as systems of one meson and one baryon, or two mesons and one baryon, with the mesons being either pseudoscalar or vectors. Connection with experiment is made including a discussion on old predictions and recent results for the photoproduction of the $\Lambda(1405)$ resonance, as well as the prediction of one $1/2^+$ baryon state around 1920 MeV which might have been seen in the $\gamma p \to K^+ \Lambda$ reaction.Comment: Talk given at the 10th International Conference on Hypernuclear and Strange Particle Physics, Tokai, Japan, Sptember 200