Perspective: Validation—What Does It Mean?

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Patrick J. Roache
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Top Down ◽  
Bottom Up ◽  
Definition Of ◽  
Journal Policies

Ambiguities, inconsistencies, and recommended interpretations of the commonly cited definition of validation for computational fluid dynamics codes/models are examined. It is shown that the definition-deduction approach is prone to misinterpretation, and that bottom-up descriptions rather than top-down legalistic definitions are to be preferred for science-based engineering and journal policies, though legalistic definitions are necessary for contracts.

Integracja w dezintegracji i dezintegracja w integracji: determinanty mechanizmów integracyjnych w Unii Europejskiej

2018 ◽  
pp. 10-37
Author(s):  
Barbara Curyło
Keyword(s):  
European Union ◽  
The European Union ◽  
Top Down ◽  
Modus Operandi ◽  
Bottom Up ◽  
Differentiated Integration ◽  
Integration Mechanisms ◽  
Strategic Issue ◽  
Definition Of ◽  
The Eu

In the discussion on the future of the EU, the topic of differentiated integration has become a strategic issue, with different variants beginning to appear as modus operandi of the European Union, which has become a subject of controversy among Member States. Significantly, the debate on differentiated integration began to be accompanied by reflections on disintegration. This article attempts to define disintegration on the assumption that it should be defined through the prism of integration, and that such a defining process can not be limited to concluding a one-way contrast between disintegration versus integration and vice versa. This is due to the assumption that the European Union is a dichotomous construct in which integration and disintegration mutually exclude and complement each other. This dichotomy is most evident in the definition of integration and disintegration through the prism of Europeanisation top-down and bottom-up processes that generate, reveal, visualize, stimulate integration mechanisms what allows to diagnose their determinants.

Efficiency limits of fans

2019 ◽  
Vol 234 (5) ◽  
pp. 739-748
Author(s):  
Konrad Bamberger ◽  
Thomas Carolus
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Geometrical Parameter ◽  
The Self ◽  
Complex Geometries ◽  
Relevant Parameter ◽  
Optimization Scheme ◽  
Loss Models ◽  
Definition Of

The purpose of this work is to identify upper efficiency limits of industrial fans such as axial rotor-only fans, axial with guide vanes, centrifugal rotor-only and centrifugal with volute. The efficiency limit is always a function of the class, the design point within the class and the definition of efficiency (total-to-static and total-to-total). The characteristic Reynolds number is another relevant parameter. First, based on analytical and empirical loss models, a theoretical efficiency limit is estimated. A set of idealizing assumptions in the loss models yields efficiencies which are assumed to be an insuperable limit but may be unrealistically high. Second, more realistic efficiency limits are estimated using a computational fluid dynamics-based optimization scheme, seeking for the best designs and hence the maximum achievable efficiencies in all classes. Given the self-imposed constraints in the geometrical parameter space considered, the thus-obtained practical efficiency limits can only be exceeded by admitting more complex geometries of the fans.

Visual Illusions?

2017 ◽  
Author(s):  
Jan Koenderink
Keyword(s):  
Partial Order ◽  
Visual Illusions ◽  
Formal Structure ◽  
Top Down ◽  
Bottom Up ◽  
Biological Approach ◽  
Definition Of

The very definition of “illusion” is elusive. Various distinct ontologies are considered. The concept is tightly bound to the understanding of reality, awareness, “God’s eye,” objectivity, subjectivity, emphatic relations, and several others. Here the distinctions between “illusion,” “ambiguity, “delusion,” and “deception,” are clarified. The very notion of illusion is closely tied to conceptual approaches to mind. Especially the dichotomy between a top-down “controlled hallucination” and a bottom-up “inverse physics” approach accounts for much confusion in the literature. It is suggested that a thoroughly biological approach might be preferable. In such an approach, experimental psychobiology would be a special sub-branch—devoted to the genus homo—of ethology. Does this help to impose a formal structure, such as a partial order, on the zoo of illusions as we know them? Unfortunately, not really. At this moment in history, we are still far from such a reasoned inventory.

scholarly journals A functional context for heterogeneity of the circadian clock in cells

PLoS Biology ◽  
2020 ◽  
Vol 18 (10) ◽  
pp. e3000927
Author(s):  
Martha Merrow ◽  
Mary Harrington
Keyword(s):  
Circadian Clock ◽  
Building Blocks ◽  
Circadian Period ◽  
Top Down ◽  
Bottom Up ◽  
Stochastic Generation ◽  
Circadian Phase ◽  
Functional Context ◽  
Definition Of

Characterization of circadian systems at the organism level—a top-down approach—has led to definition of unifying properties, a hallmark of the science of chronobiology. The next challenge is to use a bottom-up approach to show how the molecular workings of the cellular circadian clock work as building blocks of those properties. We review new studies, including a recently published PLOS Biology paper by Nikhil and colleagues, that show how programmed but also stochastic generation of variation in cellular circadian period explain important adaptive features of entrained circadian phase.

scholarly journals Assessment for the Age-Of-The-Air and Ventilation Efficiency in Confined Outdoor Spaces through Computational Fluid Dynamics Techniques

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1932 ◽  
Author(s):  
Miguel Padilla-Marcos ◽  
Meiss Alberto
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Urban Design ◽  
Considerable Improvement ◽  
Outdoor Air ◽  
Outdoor Spaces ◽  
Ventilation Efficiency ◽  
Wind Exposure ◽  
The Mean ◽  
Definition Of

An experimentally validated numerical method for evaluating the suitability of an urban design with regard to its capacity to provide the optimum air quality for its occupants through the confined outdoor spaces is proposed. Eight possible confined outdoor spaces are defined according to their position with regard to the built elements, laterally delimited by the envelope surfaces of the neighbouring buildings. This work focuses on the definition of a procedure capable of analysing outdoor air change quality according to the age-of-the-air concept. The obtained results show that the confined outdoor spaces that are exposed to the wind action are more predisposed to reduce the mean age-of-the-air that they contain. For the analysed cases, a considerable improvement of up to 78.68% in the air change quality can be obtained by taking into account wind exposure criteria in relation to its shape and urban density, which is classified for this purpose.

The Origin of Consciousness

2010 ◽  
Vol 18 (3) ◽  
pp. 481-495
Author(s):  
Jonathan Cole
Keyword(s):  
Clinical Medicine ◽  
Neural Correlates ◽  
Higher Order ◽  
Brain Anatomy ◽  
Special Issue ◽  
Top Down ◽  
Bottom Up ◽  
Neural Correlates Of Consciousness ◽  
Definition Of ◽  
External Stimuli

This paper introduces the background to the debate addressed by the papers of this Special Issue of Pragmatics & Cognition. Starting with a definition of consciousness it traces some ways in which the term is applied; from clinical medicine, where it relates somewhat crudely to responsiveness to external stimuli, to more cognitive and philosophical aspects such as higher order consciousness and its content. It then discusses the relation of consciousness to brain anatomy, the neural correlates of consciousness, and its possible evolution. In the meeting which forms the basis for Frith’s core paper, Christof Koch also made important contributions, here précised. A discussion of the origins of consciousness in relation to the top-down and bottom-up models brought to the fore follows suit.

The pragmatics of ritual

Pragmatics ◽  
2020 ◽  
Vol 30 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Dániel Z. Kádár ◽  
Juliane House
Keyword(s):  
Position Paper ◽  
Special Issue ◽  
Top Down ◽  
Bottom Up ◽  
Working Definition ◽  
Methodological Perspective ◽  
Present Collection ◽  
Definition Of

Abstract This introductory position paper aims to familiarise the reader with the pragmatics of ritual and previous research in this field. Ritual is a complex pragmatic phenomenon present in many types of interaction, and it has been subject to academic inquiries in various disciplines. We will draw on previous research to provide a working definition of ritual, which will help us to introduce the present collection of papers. We will then introduce the different, but interrelated, methodologies used in ritual research, categorising these complementary methodologies as ‘top-down’ and ‘bottom-up’ respectively. We use this categorisation to overview the contributions of the special issue from a methodological perspective. Finally, a summary of the contents of the special issue completes this introduction.

scholarly journals Velocity pick-up and discharge coefficient for round orifices with cross flow at inlet

2014 ◽  
Vol 228 (15) ◽  
pp. 2728-2737
Author(s):  
Debin Fu ◽  
John W Chew ◽  
Zixiang Sun
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Velocity Ratio ◽  
Tangential Velocity ◽  
Cross Flow ◽  
Rotating Disk ◽  
Tangential Direction ◽  
Pass Through ◽  
Definition Of ◽  
Dynamics Models

This study investigates the flow through round orifices with cross flow at the inlet. Emphasis is placed on the change in tangential velocity component for orifices with low L/ D. A definition of velocity pick-up is developed based on the orifice exit to cross-flow tangential velocity ratio. Steady, incompressible, and 3D computational fluid dynamics models with the SST [Formula: see text] turbulent model are employed to calculate orifice flows with different geometrical and flow conditions. Stationary orifices and axial orifices in a rotating disk are considered. Computational fluid dynamics solutions are compared with experimental results and published correlations for discharge coefficients, and good agreement is generally demonstrated. It is found that the non-dimensional velocity pick-up depends strongly on the ratio of characteristic times for flow to travel across the orifice in the tangential direction and that for the flow to pass through the orifice. A correlation of velocity pick-up as a function of this ratio is given.

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