764 resultados para theory to practice


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In this work a practical scheme is developed for the first-principles study of time-dependent quantum transport. The basic idea is to combine the transport master equation with the well-known time-dependent density functional theory. The key ingredients of this paper include (i) the partitioning-free initial condition and the consideration of the time-dependent bias voltages which base our treatment on the Runge-Gross existence theorem; (ii) the non-Markovian master equation for the reduced (many-body) central system (i.e., the device); and (iii) the construction of Kohn-Sham master equations for the reduced single-particle density matrix, where a number of auxiliary functions are introduced and their equations of motion (EOMs) are established based on the technique of spectral decomposition. As a result, starting with a well-defined initial state, the time-dependent transport current can be calculated simultaneously along with the propagation of the Kohn-Sham master equation and the EOMs of the auxiliary functions.

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The aim of this paper is to show that Dempster-Shafer evidence theory may be successfully applied to unsupervised classification in multisource remote sensing. Dempster-Shafer formulation allows for consideration of unions of classes, and to represent both imprecision and uncertainty, through the definition of belief and plausibility functions. These two functions, derived from mass function, are generally chosen in a supervised way. In this paper, the authors describe an unsupervised method, based on the comparison of monosource classification results, to select the classes necessary for Dempster-Shafer evidence combination and to define their mass functions. Data fusion is then performed, discarding invalid clusters (e.g. corresponding to conflicting information) thank to an iterative process. Unsupervised multisource classification algorithm is applied to MAC-Europe'91 multisensor airborne campaign data collected over the Orgeval French site. Classification results using different combinations of sensors (TMS and AirSAR) or wavelengths (L- and C-bands) are compared. Performance of data fusion is evaluated in terms of identification of land cover types. The best results are obtained when all three data sets are used. Furthermore, some other combinations of data are tried, and their ability to discriminate between the different land cover types is quantified

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Cloud point curves reported in the literature for five representatives of the system poly(vinyl methyl ether)/polystyrene were evaluated theoretically by means of the Sanchez-Lacombe lattice fluid theory. The measured phase separation behavior can be described within experimental error using only one adjustable parameter (quantifying the interaction between the unlike mers). The Flory-Huggins interaction parameters calculated from this theoretical description depend in good approximation linearly on composition (volume fractions) and on the inverse temperature. An evaluation of these data yields a maximum heat effect which is almost one order of magnitude less (ca. -0.25 J/cm(3)) than obtained via Hess's cycle (dissolution of the components and of the blend) from calorimetric measurements. Model calculations on the basis of the present theory demonstrate that the critical points shift to a different extent upon a certain relative change in the molar mass of the blend components. The sensitivity of the calculated phase diagrams against changes in the scaling parameter decreases in the following order: interaction energies between unlike mers, differences in the scaling temperatures, pressures and densities.

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We have developed a new theoretical model based on the MPB4 theory to calculate the differential capacitance of the interface of 0.05mol/L MgSO4 in water and 0.1mol/L TBATPB in nitrobenzene. Our results coincide with the experimental values very well. It indicates that our model may describe well the structure of ITIES not only in the presence of 1:1 electrolyte but also in the presence of 2:2 electrolyte.

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The MPB4 theory is used to calculate the differential capacitance of the interface between LiCl in water and TBATPB in 1,2-dichloroethane at electrolyte concentrations of 0.005, 0.01 and 0.02 M. The effects of the ion size and the image force, and the influence of the electrolyte concentration, the surface charge density and the solvent effect on the inner layer potential drop are considered simultaneously. These effects can be ascribed to the ionic penetration into the opposite solution and ion-ion correlations across the interface. Our results are in better agreement with experimental data than those obtained using Gouy-Chapman theory. This indicates that the MPB4 theory may also describe the structure of the water \1,2-dichloroethane interface provided that the influence of the electrolyte concentration, the surface charge density and the solvent effect on the inner layer potential distribution are included in the calculation. Comparison of the theoretical results with those of the water \nitrobenzene interface shows that the structure of the water \1,2-dichloroethane interface is similar to that of the water \nitrobenzene interface, except that in the former case the inner-layer potential drop is much higher and the effects of the image force and the ion size are more pronounced.

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We use the MPB4 theory to calculate the differential capacitance of the interface between NaBr + water and tetrabutylammoniumtetraphenyl borate (TBATPB) + nitrobenzene at electrolyte concentrations of 0.01 M, 0.02 M and 0.05 M. In addition to the effects

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Based on the effective medium approximation theory of composites, the empirical model proposed by Pandey and Kakar is remedied to investigate the microwave emissivity of sea surface under wave breaking driven by strong wind. In the improved model, the effects of seawater bubbles, droplets and difference in temperature of air and sea interface (DTAS) on the emissivity of sea surface covered by whitecaps are discussed. The model results indicate that the effective emissivity of sea surface increases with DTAS increasing, and the impacts of bubble structures and thickness of whitecaps layer on the emissivity are included in the model by introducing the effective dielectric constant of whitecaps layer. Moreover, a good agreement is obtained by comparing the model results with the Rose's experimental data.

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Urquhart, C. (2003). Applications of outsourcing theory to collaborative purchasing and licensing. VINE: The Journal of Information and Knowledge Management Systems, 32(4), 63-70.

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http://www.archive.org/details/theoryandpractic011935mbp

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Cultural Marxist Theory, commonly known as theory, enjoyed a moment of extraordinary success in the 1970s, when the works of leading post-war French philosophers were published in English. After relocating to Anglophone academia, however, theory disavowed its original concerns and lost its ambition to understand the world as a whole, becoming the play of heterogeneities associated with postcolonialism, multiculturalism and identity politics, commonly referred to as postmodern theory. This turn, which took place during a period that seemed to have spelt the death of Marxism, the 1990s, induced many of its supporters to engage in an ongoing funeral wake designating the merits of theory and dreaming its resurgence. According to them, had theory been resurrected in historical circumstances completely different from those which had led to its rise, it would have never reacquired the significance that had originally connoted it. This thesis demonstrates how theory has survived its demise and entirely regained its prominence in our socio-political context marked by the effects of the latest crisis of capitalism and by the global threat of terrorisms rooted in messianic eschatologies. In its current form theory does no longer need to show allegiance to certain intellectual stances or political groupings in order to produce important reformulations of the projects it once gave life to. Though less overtly radical and epistemologically bounded, theory remains a necessary form of enquiry justified by the political commitment which originated it in the first place. Its voice continues to speak to us about justice ‘where it is not yet, not yet there, where it is no longer’ (Derrida, 1993, XVIII).

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This article outlines the process of taking a manual blood pressure measurement. The author suggests that it is a skill that nursing students should be using in clinical practice rather than relying on automated monitors.