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  • 1
    Online Resource
    Online Resource
    Berlin [u.a.] : Springer
    Part of " Lecture notes in physics"
    Keywords: Turbulente Strömung ; Turbulente Strömung ; Kohärenz ; Konferenzschrift 1980 ; Turbulente Strömung ; Turbulente Strömung ; Kohärenz
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource
    ISBN: 9783540102892 , 9783540384250
    Series Statement: Lecture notes in physics 136
    RVK:
    Language: English
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of productivity analysis 8 (1997), S. 215-230 
    ISSN: 1573-0441
    Keywords: data envelopment analysis ; weight restrictions efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This paper examines the role that weight restrictions play in Data Envelopment Analysis (DEA). It is argued that the decision to include a factor (input or output) in a DEA model represents an implicit judgement that the factor has a non-trivial weight. It therefore seems perverse to allow DEA to assign a trivial weight to that factor in assessing the efficiency of a unit. There is therefore a strong case for imposing restrictions on factor weights. However, many existing methods of weight restriction are in practice unwieldy. This paper proposes an alternative approach we term contingent weight restriction which is both practical and intellectually consistent with the DEA philosophy. The paper explores the implications of alternative methods of weight restriction using simulated data from a well known production process.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 652-654 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that, in the neighborhood of a vortex whose maximum vorticity is large with respect to that in the surrounding flow, the two principal strains with the largest absolute values lie in the equatorial plane, so that the vorticity is automatically aligned to the intermediate eigenvector. This purely kinematic effect is offered as an explanation for the alignment properties recently reported for the velocity and pressure derivatives in turbulent flows. The model is compared with experimental evidence from numerical simulations. The observed ratio between the principal strains is also related to the properties of a two-dimensional Burgers' vortex.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1261-1268 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dependence of product generation on Péclet and Reynolds numbers in a numerically simulated, reacting, two-dimensional, temporally growing mixing layer is related theoretically to the fractal dimension of the passive scalar interfaces. This relation is verified using product generation measurements and fractal dimensions derived from the box counting technique. A transition from a low initial dimension to a higher one of approximately (5)/(3) is identified and shown to be associated to the kinematic distortion of the flow field during the first pairing interaction. It is suggested that the structures responsible for this transition are nondeterministic, nonrandom, inhomogeneous fractals. In the range of Schmidt numbers investigated (0.25–4), only the large scales are involved. No further transitions, either in the spectra of the vorticity field or in the mixing behavior, are found for Reynolds numbers up to 90 000.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Annals of operations research 67 (1996), S. 141-161 
    ISSN: 1572-9338
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract The performance of primary care should ultimately be judged on its effect on the health outcome of individual patients. However, for the foreseeable future, it is inconceivable that the outcome data necessary to come to a judgement on performance will be available. And in any case, specification of the statistical model necessary to analyze outcome is fraught with difficulty. This paper therefore sets out a model of primary care performance which is based on the premise that certain measurable quality indicators can act as proxies for outcome. This being the case, a model of performance can be deduced which takes into account the effect of resources and patient characteristics on outcome. The most appropriate analytic technique to make this model operational is data envelopment analysis (DEA). It is argued that DEA can handle multiple dimensions of performance more comfortably, and is less vulnerable to the misspecification bias that afflicts statistically based models. The issues are illustrated with an example from English Family Health Service Authorities.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Meccanica 29 (1994), S. 453-464 
    ISSN: 1572-9648
    Keywords: Vortices ; Turbulence ; Intermittency ; Vortex dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Sommario La struttura di regioni ad intensa vorticità in campi di flusso turbolento omogenei, isotropi ed in equilibrio, simulati numericamente, viene studiata per quattro differenti numeri di Reynolds nell'intervalloRe λ=35÷170, e si trova che tali regioni si organizzano in vortici coerenti, cilindrici o a forma di nastro (‘vermi’). Con rifermento ai numeri di Reynolds studiati, si vede che tali vortici sono responsabili per gran parte delle code estreme ed intermittenti, osservate nelle statistiche dei gradienti di velocità, ma la loro importanza sembra decrescere a più altiRe λ. I loro raggi scalano con la microscala di Kolmogorov e le loro lunghezze con la scala integrale del flusso, mentre la loro circolazione cresce monotonicamente conRe λ. Per quest'ultimo riscalamento viene offerta una spiegazione basata sull'assunzione della presenza di onde inerziali assiali lungo i loro nuclei, eccitate da una deformazione di fondo casuale dell'ordine della radice quadrata della velocità media. Questa spiegazione è consistente con la presenza di incrementi paragonabili di allungamenti e compressioni lungo i nuclei dei vortici.
    Notes: Abstract The structure of the intense vorticity regions is studied in numerically simulated homogeneous, isotropic, equilibrium turbulent flow fields at four different Reynolds numbers, in the rangeRe λ=35–170, and is found to be organized in coherent, cylindrical or ribbon-like, vortices (‘worms’). At the Reynolds numbers studied, they are responsible for much of the extreme intermittent tails observed in the statistics of the velocity gradients, but their importance seems to decrease at higherRe λ. Their radii scale with the Kolmogorov microscale and their lengths with the integral scale of the flow, while their circulation increases monotonically withRe λ. An explanation is offered for this latter scaling, based in the assumed presence of axial inertial waves along their cores, excited by a random background strain of the order of the root mean square vorticity. This explanation is consistent with the presence of comparable amounts of stretching and compression along the vortex cores.
    Type of Medium: Electronic Resource
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  • 7
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    Louvain-la-Neuve: European Regional Science Association (ERSA)
    Publication Date: 2015-09-11
    Description: The study of corruption is attracting lot of attention in recent years. Focusing on the economic consequences of corruption, the empirical evidence points to a positive relation between institutional integrity, or absence of corruption, and economic growth. Although most developed countries tend to have lower corruption than less developed ones, there exists significant variation within OECD countries. As an example, it may be observed that the gap in perceived corruption between the Nordic countries and southern Europe is larger than the gap between southern Europe and the average of the emerging economies. In this context, the objective of this paper is to analyze the impact of corruption on economic performance in a sample of OECD countries during the period 1980-2000. Specifically, we study the effect of corruption on productivity and efficiency change, trying to determine whether productivity growth is greater in countries with lower corruption. To this end, different productivity measures are compared by considering both output per worker and Total Factor Productivity (TFP). Furthermore, TFP change is decomposed into efficiency change and technological progress by means of Malmquist productivity indices. On the basis of this of this decomposition we will analyze whether corruption affect TFP growth via efficiency gains or technological change, thus gaining insight into the channels through which corruption influence economic growth.
    Keywords: ddc:330
    Language: English
    Type: doc-type:conferenceObject
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  • 8
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    Unknown
    Louvain-la-Neuve: European Regional Science Association (ERSA)
    Publication Date: 2015-09-05
    Description: The main objective of this paper is to provide a general analysis of the evolution of the funding models of the Spanish Autonomous Communities (regional level) during the last decade and explore the main achievements of the new model (2001). In particular, the funding models that have been applied during these years are assessed comparing their results with the proponsed objectives that they tried to meet. Finally, special attention is paid to the developments achieved by the new model with respect to the previous one in terms of economic sufficiency (static and dynamic), joint responsibility for taxation and interregional solidarity measures. Key words: Federalismo Fiscal, Spanish Autonomous Communities, Economic Sufficiency, Fiscal Corresponsability, Interregional Solidarity. JEL classification: H7, H72, H77
    Keywords: H7 ; H72 ; H77 ; ddc:330 ; Federalismo Fiscal ; Spanish Autonomous Communities ; Economic Sufficiency ; Fiscal Corresponsability ; Interregional Solidarity
    Language: English
    Type: doc-type:conferenceObject
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 31 (1988), S. 1311-1313 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure of the vorticity field in the viscous wall layer of a turbulent channel is studied by examining the results of a fully resolved direct numerical simulation. It is shown that this region is dominated by intense three-dimensional shear layers in which the dominant vorticity component is spanwise. The advection and reproduction processes of these structures are examined and shown to be consistent with the classical generation mechanism for two-dimensional Tollmien–Schlichting waves. This process is fundamentally different from the usually accepted mechanism involving hairpin vortices.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 3644-3646 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The bifurcations to two-dimensional unsteady behavior of a large amplitude equilibrium shear wave train in two-dimensional Poiseuille flow are studied by direct simulation of the time evolution of the full Navier–Stokes equations. It is found that the wave train becomes unstable at Re∼5600, and sheds a limit cycle which, at higher Re, seems to undergo further transitions to more complex behaviors. It is shown that the site of the original bifurcation is in the neighborhood of the walls and that it shows some characteristics suggestive of the burst generation mechanism in the boundary layer.
    Type of Medium: Electronic Resource
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