On the Evolution of Preferences

A common feature of the literature on the evolution of preferences is that evolution favors nonmaterialistic preferences only if preference types are observable at least to some degree. We argue that this result is due to the assumption that in each state of the evolutionary dynamics some Bayesian Nash equilibrium is played. We show that under unobservability of preference types, conditional on selecting some self-confirming equilibrium as a rule for mapping preference into behavior, non-selfish preferences may be evolutionarily successful.evolution of preferences, altruism, learning, self-confirming equilibrium

Policy-Motivated Candidates, Noisy Platforms, and Non-Robustness

A model of a two-candidate election is developed in which the candidates are mainly office-motivated but also to some arbitrarily small extent policy-motivated, and their chosen platforms are to some arbitrarily small extent noisy. The platforms’ being noisy means that if a candidate has chosen a particular platform, the voters’ perception is that she has, with positive probability, actually chosen some other platform. It is shown that (i) an equilibrium in which the candidates play pure exists whether or not there is a Condorcet winner among the policy alternatives, and (ii) in this equilibrium the candidates choose their ideal points, which means that the platforms do not converge. ZUSAMMENFASSUNG - (Politikmotivierte Kandidaten, Plattformen mit Rauschen und Nichtrobustheit) In der Arbeit werden die Bedingungen identifiziert, unter denen im Gleichgewicht eines symmetrischen Modells einige, in der Produktionskette vorgelagerte Firmen vertikale Trennung wählen, während andere sich für vertikale Integration entscheiden. Ein vertikal getrenntes Unternehmen wägt die fixen Vertragskosten gegen den strategischen Vorteil eines Vertrages (mit gespaltenem Tarif und exklusiven Vertriebsrechten) mit dem nachgelagerten Einzelhändler ab. Die Koexistenz der beiden Organisationsformen im Gleichgewicht entsteht, wenn den nachgelagerten Cournot-Oligopolisten, die fast perfekte Substitute produzieren, beobachtbare und nicht nachverhandelbare Verträge angeboten werden. Die Koexistenz der Organisationsformen im Gleichgewicht tritt weniger häufig auf, wenn die Annahmen bezüglich der Beobachtbarkeit der Verträge und der Möglichkeit sich zu binden, gelockert werden.Electoral Competition; Policy Motivation; Noisy Commitment; Convergence; Robustness

Observations and asteroseismic analysis of the rapidly pulsating hot B subdwarf PG 0911+456

The principal aim of this project is to determine the structural parameters of the rapidly pulsating subdwarf B star PG 0911+456 from asteroseismology. Our work forms part of an ongoing programme to constrain the internal characteristics of hot B subdwarfs with the long-term goal of differentiating between the various formation scenarios proposed for these objects. First comparisons of asteroseismic values with evolutionary theory look promising, however it is clear that more targets are needed for meaningful statistics to be derived. The observational pulsation periods of PG 0911+456 were extracted from rapid time-series photometry using standard Fourier analysis techniques. Supplemented by spectroscopic estimates of the star's mean atmospheric parameters, they were used as a basis for the "forward modelling" approach in asteroseismology. The latter culminates in the identification of one or more "optimal" models that can accurately reproduce the observed period spectrum. This naturally leads to an identification of the oscillations detected in terms of degree l and radial order k, and infers the structural parameters of the target. From the photometry it was possible to extract 7 independent pulsation periods in the 150-200 s range with amplitudes between 0.05 and 0.8 % of the star's mean brightness. An asteroseismic search of parameter space identified several models that matched the observed properties of PG 0911+456 well, one of which was isolated as the "optimal" model on the basis of spectroscopic and mode identification considerations. All the observed pulsations are identified with low-order acoustic modes with degree indices l=0,1,2 and 4, and match the computed periods with a dispersion of only ~0.26 %.Comment: accepted for publication in A&A, 14 pages, 13 figure

Model predictive control techniques for hybrid systems

This paper describes the main issues encountered when applying model predictive control to hybrid processes. Hybrid model predictive control (HMPC) is a research field non-fully developed with many open challenges. The paper describes some of the techniques proposed by the research community to overcome the main problems encountered. Issues related to the stability and the solution of the optimization problem are also discussed. The paper ends by describing the results of a benchmark exercise in which several HMPC schemes were applied to a solar air conditioning plant.Ministerio de Eduación y Ciencia DPI2007-66718-C04-01Ministerio de Eduación y Ciencia DPI2008-0581

On the observability of bow shocks of Galactic runaway OB stars

Massive stars that have been ejected from their parent cluster and supersonically sailing away through the interstellar medium (ISM) are classified as exiled. They generate circumstellar bow shock nebulae that can be observed. We present two-dimensional, axisymmetric hydrodynamical simulations of a representative sample of stellar wind bow shocks from Galactic OB stars in an ambient medium of densities ranging from n_ISM=0.01 up to 10.0/cm3. Independently of their location in the Galaxy, we confirm that the infrared is the most appropriated waveband to search for bow shocks from massive stars. Their spectral energy distribution is the convenient tool to analyze them since their emission does not depend on the temporary effects which could affect unstable, thin-shelled bow shocks. Our numerical models of Galactic bow shocks generated by high-mass (~40 Mo) runaway stars yield H$\alpha$ fluxes which could be observed by facilities such as the SuperCOSMOS H-Alpha Survey. The brightest bow shock nebulae are produced in the denser regions of the ISM. We predict that bow shocks in the field observed at Ha by means of Rayleigh-sensitive facilities are formed around stars of initial mass larger than about 20 Mo. Our models of bow shocks from OB stars have the emission maximum in the wavelength range 3 <= lambda <= 50 micrometer which can be up to several orders of magnitude brighter than the runaway stars themselves, particularly for stars of initial mass larger than 20 Mo.Comment: 13 pages, 12 figures. Accepted to MNRAS (2016

Recycling neutron stars to ultra short periods: a statistical analysis of their evolution in the mu-P plane

We investigate the statistical evolution of magnetic neutron stars, recycled in binary systems, simulating synthetic populations. To bracket uncertainties, we consider a soft (FP) and a stiff (PS) equation of state (EoS) for nuclear matter and explore the hypothesis that the magnetic field is confined in the stellar crust. We follow the magneto-rotational evolution within a simple recycling scenario, including the possibility of magnetospheric propeller. We find the presence of a tail in the period distribution of the synthetic populations at periods shorter than 1.558 ms, the minimum detected so far. For the soft EoS the recycling gives rise to a spin distribution which is increasing monotonically toward short periods and a clear ``barrier'' forms at the minimum period for the onset of mass shedding. For the stiff EoS the distribution is flatter displaying a broad maximum about 2-4 ms. The estimated fraction of neutron stars spinning close to their shedding limit over the millisecond pulsar population is found to be significant. Crustal magnetic field decay models predict the existence of massive (M>1.4 M_sun) rapidly spinning neutron stars with very low magnetic moment.Comment: 34 pages, 2 tables, 9 figures, Latex. Accepted (5 Jul 99) for publication in the Astrophysical Journal Supplement

Partner Choice and Morality: Preference Evolution under Stable Matching

We present a model that investigates preference evolution with endogenous matching. In the short run, individuals' subjective preferences simultaneously determine who they choose to match with and how they behave in the social interactions with their matched partners, which result in material payoffs for them. Material payoffs in turn affect how preferences evolve in the long run. To properly model the "match-to-interact" process, we combine stable matching and equilibrium concepts. Our analysis unveils that endogenous matching gives rise to the "we is greater than me" moral perspective. This perspective is underpinned by a preference that exhibits both homophily and efficiency, which enables individuals to reach a consensus of a collective ``we" that transcends the boundaries of the individual "I" and "you." Such a preference stands out in the evolutionary process because it is able to force positive assortative matching and efficient play among individuals carrying the same preference type. Under incomplete information, a strong form of homophily, which we call parochialism, is necessary for a preference to prevail in evolution, because stronger incentives are required to engage in self-sorting with information friction

Analysis of Line Outage Detection in Nigeria 330kV Transmission Lines using Phasor Measurement Units

In this work, an analysis of line outage detection in Nigeria 330kV transmission lines using Phasor Measurement Units was presented. This requires collection and analysis of the data obtained from Transmission Company of Nigeria with the aid of PSAT 2.10.1 / MATLAB SIMULINK using Newton-Raphson power flow algorithm and also to determine the effectiveness of PMU when introduced in our power system network. 12 buses and 3 Generators system were considered for the studied.&nbsp;This was achieved by collecting relevant transmission parameters for 330kV line and was simulated on PSAT 2.10.1 and MATLAB 2015a using Newton-Raphson power flow algorithm. The work involved an offline and online analysis. For the offline analysis the admittance / impedance matrix for Y-bus and bus voltage for pre-outage was obtained via the power flow analysis and change in impedance for the lines were calculated. These values were further normalised in order to reduce the value to a row echelon form. Then for the online analysis; the change in phase angle from the Phasor Measurement Unit (PMU) online simulation for pre-outage and also post-outage was calculated and a normalised column matrix was gotten.&nbsp;Finally, the effectiveness of the line outage detection was graphically represented using MATLAB software to plot the values of the normalised values of the offline and online analysis; i.e., by comparing the normalised form of the offline and online values. These results clearly show that PMUs gives an accurate monitoring and total observability when introduced in Nigeria power system

Coevolution of Deception and Preferences: Darwin and Nash Meet Machiavelli

We develop a framework in which individuals preferences co-evolve with their abilities to deceive others regarding their preferences and intentions. We show that a pure outcome is stable, essentially if and only if it is an efficient Nash equilibrium. All individuals have the same deception ability in such a stable state. In contrast, there are non-pure outcomes in which non-Nash outcomes are played, and different deception abilities co-exist. We extend our model to study preferences that depend also on the opponent's type