Extremal principle of entropy production in the climate system

Paltridge found reasonable values for the most significant climatic variables through maximizing the material transport part of entropy production by using a simple box model. Here, we analyse Paltridge's box model to obtain the energy and the entropy balance equations separately. Derived expressions for global entropy production, which is a function of the radiation field, and even its material transport component, are shown to be different from those used by Paltridge. Plausible climatic states are found at extrema of these parameters. Feasible results are also obtained by minimizing the radiation part of entropy production, in agreement with one of Planck's results, Finally, globally averaged values of the entropy flux of radiation and material entropy production are obtained for two dynamical extreme cases: an earth with uniform temperature, and an earth in radiative equilibrium at each latitudinal point

A systematic and feasible method for computing nuclear contributions to electrical properties of polyatomic molecules

An analytic method to evaluate nuclear contributions to electrical properties of polyatomic molecules is presented. Such contributions control changes induced by an electric field on equilibrium geometry (nuclear relaxation contribution) and vibrational motion (vibrational contribution) of a molecular system. Expressions to compute the nuclear contributions have been derived from a power series expansion of the potential energy. These contributions to the electrical properties are given in terms of energy derivatives with respect to normal coordinates, electric field intensity or both. Only one calculation of such derivatives at the field-free equilibrium geometry is required. To show the useful efficiency of the analytical evaluation of electrical properties (the so-called AEEP method), results for calculations on water and pyridine at the SCF/TZ2P and the MP2/TZ2P levels of theory are reported. The results obtained are compared with previous theoretical calculations and with experimental values

Additional compact formulas for vibrational dynamic dipole polarizabilities and hyperpolarizabilities

Compact expressions, complete through second order in electrical and/or mechanical anharmonicity, are given for the dynamic dipole vibrational polarizability and dynamic first and second vibrational hyperpolarizabilities. Certain contributions not previously formulated are now included

Negative Fukui functions: new insights based on electronegativity equalization

The occurrence of negative values for Fukui functions was studied through the electronegativity equalization method. Using algebraic relations between Fukui functions and different other conceptual DFT quantities on the one hand and the hardness matrix on the other hand, expressions were obtained for Fukui functions for several archetypical small molecules. Based on EEM calculations for large molecular sets, no negative Fukui functions were found

Critical thoughts on computing atom condensed Fukui functions

Different procedures to obtain atom condensed Fukui functions are described. It is shown how the resulting values may differ depending on the exact approach to atom condensed Fukui functions. The condensed Fukui function can be computed using either the fragment of molecular response approach or the response of molecular fragment approach. The two approaches are nonequivalent; only the latter approach corresponds in general with a population difference expression. The Mulliken approach does not depend on the approach taken but has some computational drawbacks. The different resulting expressions are tested for a wide set of molecules. In practice one must make seemingly arbitrary choices about how to compute condensed Fukui functions, which suggests questioning the role of these indicators in conceptual density-functional theory

Nuclear relaxation contribution to static and dynamic (infinite frequency approximation) nonlinear optical properties by means of electrical property expansions: Application to HF, CH4, CF4, and SF6

Electrical property derivative expressions are presented for the nuclear relaxation contribution to static and dynamic (infinite frequency approximation) nonlinear optical properties. For CF4 and SF6, as opposed to HF and CH4, a term that is quadratic in the vibrational anharmonicity (and not previously evaluated for any molecule) makes an important contribution to the static second vibrational hyperpolarizability of CF4 and SF6. A comparison between calculated and experimental values for the difference between the (anisotropic) Kerr effect and electric field induced second-harmonic generation shows that, at the Hartree-Fock level, the nuclear relaxation/infinite frequency approximation gives the correct trend (in the series CH4, CF4, SF6) but is of the order of 50% too small

Nuevo disipador para edificación sismorresistente. 1ª parte: caracterización y modelos de predicción

A new energy dissipator, based on yielding of steel under shear response, has been developed and recently tested. It is H shaped and web stiffened. Yielding moin part is mechanized from one piece of rectangular shoped steel bar. Its conception let obtain thin and well-stiffened web cross sections without welded parts. Main experimentally obtained charecteristics are a yielding point near 0.5 mm of displacement, yielding loads between 14 kN and 20 kN and a dissipated energy, before damage appears in the web, from 10 kJ to 21 kJ. All tested specimens have developed large deformations without web buckling. Whe web degradation appers, flanges and stiffeners keep dissipating an important amount of energy. Proposed numerical models and simple mathematical expressions offer well correlated results when compared to the experimental ones

Interplay of spectral efficiency, power and doppler spectrum for reference-signal-assisted wireless communication

Expressions relating spectral efficiency, power, and Doppler spectrum, are derived for Rayleigh-faded wireless channels with Gaussian signal transmission. No side information on the state of the channel is assumed at the receiver. Rather, periodic reference signals are postulated in accordance with the functioning of most wireless systems. The analysis relies on a well-established lower bound, generally tight and asymptotically exact at low SNR. In contrast with most previous studies, which relied on block-fading channel models, a continuous-fading model is adopted. This embeds the Doppler spectrum directly in the derived expressions, imbuing them with practical significance. Closed-form relationships are obtained for the popular Clarke-Jakes spectrum and informative expansions, valid for arbitrary spectra, are found for the low- and high-power regimes. While the paper focuses on scalar channels, the extension to multiantenna settings is also discussed.

High-SNR power offset in multiantenna communication

The analysis of the multiantenna capacity in the high-SNR regime has hitherto focused on the high-SNR slope (or maximum multiplexing gain), which quantifies the multiplicative increase as function of the number of antennas. This traditional characterization is unable to assess the impact of prominent channel features since, for a majority of channels, the slope equals the minimum of the number of transmit and receive antennas. Furthermore, a characterization based solely on the slope captures only the scaling but it has no notion of the power required for a certain capacity. This paper advocates a more refined characterization whereby, as function of SNRjdB, the high-SNR capacity is expanded as an affine function where the impact of channel features such as antenna correlation, unfaded components, etc, resides in the zero-order term or power offset. The power offset, for which we find insightful closed-form expressions, is shown to play a chief role for SNR levels of practical interest.

Multiuser detection in a dynamic environment — Part II: Joint user identification and parameter estimation

The problem of jointly estimating the number, the identities, and the data of active users in a time-varying multiuser environment was examined in a companion paper (IEEE Trans. Information Theory, vol. 53, no. 9, September 2007), at whose core was the use of the theory of finite random sets on countable spaces. Here we extend that theory to encompass the more general problem of estimating unknown continuous parameters of the active-user signals. This problem is solved here by applying the theory of random finite sets constructed on hybrid spaces. We doso deriving Bayesian recursions that describe the evolution withtime of a posteriori densities of the unknown parameters and data.Unlike in the above cited paper, wherein one could evaluate theexact multiuser set posterior density, here the continuous-parameter Bayesian recursions do not admit closed-form expressions. To circumvent this difficulty, we develop numerical approximationsfor the receivers that are based on Sequential Monte Carlo (SMC)methods (“particle filtering”). Simulation results, referring to acode-divisin multiple-access (CDMA) system, are presented toillustrate the theory.

Outage probability analysis for MRC in η-μ fading channels with co-channel interference

Exact closed-form expressions are obtained for the outage probability of maximal ratio combining in η-μ fadingchannels with antenna correlation and co-channel interference. The scenario considered in this work assumes the joint presence of background white Gaussian noise and independent Rayleigh-faded interferers with arbitrary powers. Outage probability results are obtained through an appropriate generalization of the moment-generating function of theη-μ fading distribution, for which new closed-form expressions are provided.

Spectral efficiency in reference-signal-assisted low-power wireless communication

Expressions relating spectral efficiency, power and Doppler spectrum are derived for low-power Rayleighfaded wireless channels with proper complex signaling. Noside information on the state of the channel is assumed at the receiver. Rather, periodic reference signals are postulated inaccordance with the functioning of most wireless systems. In contrast with most previous studies, which relied on block-fading channel models, a continuous-fading model is adopted. This embeds the Doppler spectrum directly in thederived expressions thereby imbuing them with practical significance.

Using qualia information to identify lexical semantic classes in an unsupervised clustering task

Acquiring lexical information is a complex problem, typically approached by relying on a number of contexts to contribute information for classification. One of the first issues to address in this domain is the determination of such contexts. The work presented here proposes the use of automatically obtained FORMAL role descriptors as features used to draw nouns from the same lexical semantic class together in an unsupervised clustering task. We have dealt with three lexical semantic classes (HUMAN, LOCATION and EVENT) in English. The results obtained show that it is possible to discriminate between elements from different lexical semantic classes using only FORMAL role information, hence validating our initial hypothesis. Also, iterating our method accurately accounts for fine-grained distinctions within lexical classes, namely distinctions involving ambiguous expressions. Moreover, a filtering and bootstrapping strategy employed in extracting FORMAL role descriptors proved to minimize effects of sparse data and noise in our task.

Teaching Literature in EFL through the Story Grammar and Reader Response Approach

La Literatura ha de ser implementada a les aules com a eina per a l’ensenyament i aprenentatge de la llengua anglesa, i hauria de complementar els llibres de text d’ensenyament d’aquesta llengua. D’aquesta manera els alumnes seran exposats encara més a una varietat de registres, expressions i vocabulari d’aquesta llengua. La metodologia d’ensenyar la gramàtica dels contes o històries coneguda en anglès com “Story Grammar Approach” (SGA) i la metodologia sobre la comprensió i reacció lectora o “Reader Response Approach” (RRA) són excel•lent vehicles per a implementar la Literatura com a eina a les aules per a ensenyar anglès.La metodologia sobre la gramàtica de contes o “SGA” només es pot posar en pràctica quan els textos són narratius perquè aquests posseeixen tots els següents elements:• Personatges• Ambient• Trama• Conflicte• Resolució• Tema La metodologia de la reacció lectiva o “RRA” es centra principalment en la comprensió subjectiva i reacció del lector sobre un text, en la qual el lector formula una hipòtesis i aporta les seves idees sobre el text a una conversa grupal. Els estudiants han de poder aportar les seves reaccions, idees i respostes sobre els textos. La metodologia “RRA” també enfoca les habilitats cognitives superiors i empenya a l’alumne a millorar la seva expressió oral.Aquestes dues metodologies aporten incomptable avantatges. Treballen totes les intel•ligències múltiples i totes les competències acadèmiques (menys la matemàtica), els alumnes aprenen a treballar i a escolar als altres (i valorar altres opinions), poden aprendre sobre diferents cultures, la història, geografia, són exposats a diferents gèneres, i fomenten i estimulen la lectura i escriptura, com també treballen les habilitats productives i receptives en l’aprenentatge del anglès.

Els Colors : estratègia i imatge empresarial

L’estudi presentat en aquest informe correspon a la investigació al voltant del paper del color al màrqueting empresarial. La seva influència, ja sigui com a eina comunicativa o identificadora d’un producte o empresa, es torna molt superior a la qualse li podria atribuir en un primer moment (fins al punt de convertir-se en un aspecte clau) quan s’observa la reacció dels consumidors davant les seves variacions i l’aplicació que en fan les companyies.La primera idea a confirmar pel treball és el caràcter inconscient de les reaccions generades per la percepció visual i les motivacions existents per explotarles.Un estudi sobre els precursors i les teories actuals de la psicologia del color condueix a una comparació entre allò que reflecteixen els estudis amb la realitat empresarial actual, mostrant una correlació evident entre valors de les organitzacions iles seves expressions pictòriques i exemplificant situacions de coincidència entre canvi de color i canvi d’estratègia corporativa. Aquest procés dóna lloc a la hipòtesi principal: el color és un element indispensable del procés de comercialització.Per tal de contrastar-la, inicialment s’acudirà a l’evidència recaptada mitjançant un qüestionari d’elaboració pròpia. A partir dels seus resultats, observarem com els consumidors no creuen estar tan influenciats per l’estètica i el color dels productes que compren com efectivament ho estan, i podrem seguir reafirmant la teoria exposada a la primera part amb paral·lelismes respecte les opinions mostrades.A continuació, es reflexionarà sobre quatre funcions del color aplicades a l’empresa de les quals aquestes es poden beneficiar: segmentador de mercats, indicador de canvi de tendència, identificador nacional i element associatiu immediat.Les determinacions preses a cada apartat a partir de reflexions teòriques i exemples formaran un entramat de conclusions que posarà fi al projecte en un apartat en el quals’ordenen les bases per a la correcta aplicació del color al món empresarial, en funció del rol de la companyia dins del seu mercat, els valors a transmetre, el tipus de producte a comerciar, etc.Finalment, els nombrosos fonaments que se li poden atribuir a favor fan que lahipòtesi inicial quedi ratificada com a certa, ja que es demostrarà una permanent voluntat per part de les empreses d’influir sobre el comportament dels destinataris del seu procés publicitari mitjançant aquest recurs, ja sigui de manera directa o indirecta.