6,235 research outputs found

    PURDU-WINCOF: A computer code for establishing the performance of a fan-compressor unit with water ingestion

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    A model for predicting the performance of a multi-spool axial-flow compressor with a fan during operation with water ingestion was developed incorporating several two-phase fluid flow effects as follows: (1) ingestion of water, (2) droplet interaction with blades and resulting changes in blade characteristics, (3) redistribution of water and water vapor due to centrifugal action, (4) heat and mass transfer processes, and (5) droplet size adjustment due to mass transfer and mechanical stability considerations. A computer program, called the PURDU-WINCOF code, was generated based on the model utilizing a one-dimensional formulation. An illustrative case serves to show the manner in which the code can be utilized and the nature of the results obtained

    Ipteks Peraturan Pemerintah No.71 Tahun 2010 Tentang Akuntansi Pemerintahan Berbasis Akrual pada Badan Penanggulangan Bencana Daerah Provinsi Sulawesi Utara

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    Organization of Prov. Regional Disaster Management Agency North Sulawesi Moves in the Field of Disaster Management Operations Centers which need to implement Government Regulation No. 71 of 2010 on accrual bases to provide information from financial records and facilitate more effective performance. In accounting there are two records of the first cash basis and accrual basis. Accrual Basis is the basis for facilitating performance measurement, in regulating clearer and more understandable. This study uses descriptive research methods that aim to explain the circumstances, events or everything related to programs that can be explained in words or numbers. The application of Government Regulation No. 71 of 2010 concerning accrual basis is certainly in accordance with what has been implemented by the Law that has been implemented by the government, Government Accounting Standards, Financial Accounting Standards. Accrual basis application needs financial statements, so that problems can be found or what things are not in accordance with the activities of either budgeting or calculation of budgeting

    From vocational training to education: the development of a no-frontiers education policy for Europe?

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    This article focuses on developments towards an EU educational policy. Education was not included as one of the Community competencies in the Treaty of Rome. The first half of the article analyses the way that the European Court of Justice and the Commission of the European Communities between them managed to develop a series of substantial Community programmes out of Article 128 on vocational training. The second half of the article discusses educational developments in the community following the Treaty on European Union and the Treaty of Amsterdam. Whilst the legal competence of the community now includes education, the author's argument is that the inclusion of an educational competence will not result in further developments to mirror those in the years before the Treaty on Europe</p

    High frequency dynamics in a monatomic glass

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    The high frequency dynamics of glassy Selenium has been studied by Inelastic X-ray Scattering at beamline BL35XU (SPring-8). The high quality of the data allows one to pinpoint the existence of a dispersing acoustic mode for wavevectors (QQ) of 1.5<Q<12.51.5<Q<12.5 nm1^{-1}, helping to clarify a previous contradiction between experimental and numerical results. The sound velocity shows a positive dispersion, exceeding the hydrodynamic value by \approx 10% at Q<3.5Q<3.5 nm1^{-1}. The Q2Q^2 dependence of the sound attenuation Γ(Q)\Gamma(Q), reported for other glasses, is found to be the low-QQ limit of a more general Γ(Q)Ω(Q)2\Gamma(Q) \propto \Omega(Q)^2 law which applies also to the higher QQ region, where Ω(Q)Q\Omega(Q)\propto Q no longer holds.Comment: Phys. Rev. Lett. (Accepted

    The influence of the Lande gg-factor in the classical general relativistic description of atomic and subatomic systems

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    We study the electromagnetic and gravitational fields of the proton and electron in terms of the Einstenian gravity via the introduction of an arbitrary Lande gg-factor in the Kerr-Newman solution. We show that at length scales of the order of the reduced Compton wavelength, corrections from different values of the gg-factor are not negligible and discuss the presence of general relativistic effects in highly ionized heavy atoms. On the other hand, since at the Compton-wavelength scale the gravitational field becomes spin dominated rather than mass dominated, we also point out the necessity of including angular momentum as a source of corrections to Newtonian gravity in the quantum description of gravity at this scale.Comment: 11 pages, 2 figure

    Weakly frustrated two-dimensional Heisenberg antiferromagnets: thermodynamic properties from a non-perturbative approach

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    We analyze the thermodynamic properties of the spin-S two-dimensional quantum Heisenberg antiferromagnet on a square lattice with nearest and next-nearest neighbor couplings in the Neel phase (J_2/J_1<0.4) employing the quantum hierarchical reference theory (QHRT), a non-perturbative implementation of the renormalization group method to quantum systems. We investigate the staggered susceptibility, the structure factors and the correlation length at finite temperature and for different values of the frustration ratio. From the finite temperature results, we also extrapolate ground state properties, such as spin stiffness and spontaneous staggered magnetization, providing an estimate of the extent of quantum corrections. The behavior of these quantities as a function of frustration may provide some hint on the breakdown of the Neel phase at zero temperature for larger values of J_2

    A gauge invariant study of the monopole condensation in non Abelian lattice gauge theories

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    We investigate the Abelian monopole condensation in finite temperature SU(2) and SU(3) pure lattice gauge theories. To this end we introduce a gauge invariant disorder parameter built up in terms of the lattice Schr\"odinger functional. Our numerical results show that the disorder parameter is different from zero and Abelian monopole condense in the confined phase. On the other hand our numerical data suggest that the disorder parameter tends to zero, in the thermodynamic limit, when the gauge coupling constant approaches the critical deconfinement value. In the case of SU(3) we also compare the different kinds of Abelian monopoles which can be defined according to the choice of the Abelian subgroups.Comment: 18 pages, 7 figures, LaTe

    The Effective Field Theory of Inflation

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    We study the effective field theory of inflation, i.e. the most general theory describing the fluctuations around a quasi de Sitter background, in the case of single field models. The scalar mode can be eaten by the metric by going to unitary gauge. In this gauge, the most general theory is built with the lowest dimension operators invariant under spatial diffeomorphisms, like g^{00} and K_{mu nu}, the extrinsic curvature of constant time surfaces. This approach allows us to characterize all the possible high energy corrections to simple slow-roll inflation, whose sizes are constrained by experiments. Also, it describes in a common language all single field models, including those with a small speed of sound and Ghost Inflation, and it makes explicit the implications of having a quasi de Sitter background. The non-linear realization of time diffeomorphisms forces correlation among different observables, like a reduced speed of sound and an enhanced level of non-Gaussianity.Comment: 26 pages. v2: minor corrections, JHEP published versio

    Intersecting Flavor Branes

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    We consider an instance of the AdS/CFT duality where the bulk theory contains an open string tachyon, and study the instability from the viewpoint of the boundary field theory. We focus on the specific example of the AdS_5 X S^5 background with two probe D7 branes intersecting at general angles. For generic angles supersymmetry is completely broken and there is an open string tachyon between the branes. The field theory action for this system is obtained by coupling to N =4 super Yang-Mills two N =2 hyper multiplets in the fundamental representation of the SU(N) gauge group, but with different choices of embedding of the two N=2 subalgebras into N=4. On the field theory side we find a one-loop Coleman-Weinberg instability in the effective potential for the fundamental scalars. We identify a mesonic operator as the dual of the open string tachyon. By AdS/CFT, we predict the tachyon mass for small 't Hooft coupling (large bulk curvature) and confirm that it violates the AdS stability bound.Comment: 36 page

    Cosmological Non-Linearities as an Effective Fluid

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    The universe is smooth on large scales but very inhomogeneous on small scales. Why is the spacetime on large scales modeled to a good approximation by the Friedmann equations? Are we sure that small-scale non-linearities do not induce a large backreaction? Related to this, what is the effective theory that describes the universe on large scales? In this paper we make progress in addressing these questions. We show that the effective theory for the long-wavelength universe behaves as a viscous fluid coupled to gravity: integrating out short-wavelength perturbations renormalizes the homogeneous background and introduces dissipative dynamics into the evolution of long-wavelength perturbations. The effective fluid has small perturbations and is characterized by a few parameters like an equation of state, a sound speed and a viscosity parameter. These parameters can be matched to numerical simulations or fitted from observations. We find that the backreaction of small-scale non-linearities is very small, being suppressed by the large hierarchy between the scale of non-linearities and the horizon scale. The effective pressure of the fluid is always positive and much too small to significantly affect the background evolution. Moreover, we prove that virialized scales decouple completely from the large-scale dynamics, at all orders in the post-Newtonian expansion. We propose that our effective theory be used to formulate a well-defined and controlled alternative to conventional perturbation theory, and we discuss possible observational applications. Finally, our way of reformulating results in second-order perturbation theory in terms of a long-wavelength effective fluid provides the opportunity to understand non-linear effects in a simple and physically intuitive way.Comment: 84 pages, 3 figure
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