Theoretical Investigations

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Theoretical Investigations

Gerry Stahl
Theoretical Investigations Book PDF

Author : Gerry Stahl
Publisher : Springer Nature
Page : 604 pages
File Size : 41,7 Mb
Release : 2021-04-23
Category : Education
ISBN : 9783030491574

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Theoretical Investigations by Gerry Stahl Pdf

Computers have transformed how we think, discuss and learn—as individuals, in groups, within cultures and globally. However, social media are problematic, fostering flaming, culture wars and fake news. This volume presents an alternative paradigm for computer support of group thinking, collaborative learning and joint knowledge construction. This requires expanding concepts of cognition to collectivities, like collaborative groups of networked students. Theoretical Investigations explores the conditions for group cognition, supplying a philosophical foundation for new models of pedagogy and methods to analyze group interaction. Twenty-five self-contained investigations document progress in research on computer-supported collaborative learning (CSCL)—both in Stahl’s own research and during the first decade of the CSCL journal. The volume begins with two new reflections on the vision and theory that result from this research. Representing both ethnomethodological and social-constructivist research paradigms, the investigations within this volume comprise a selection of seminal and influential articles and critical commentaries that contribute to an understanding of concepts and themes central to the CSCL field. The book elaborates an innovative theory of group cognition and substantiates the pedagogical potential of CSCL. Theoretical Investigations: Philosophical Foundations of Group Cognition is essential as a graduate text for courses in educational theory, instructional design, learning and networked technologies. The investigations will also appeal to researchers and practitioners in those areas.

Theoretical Investigations on the Efficiency and the Conditions for the Realization of Jet Engines

Maurice Roy
Theoretical Investigations on the Efficiency and the Conditions for the Realization of Jet Engines Book PDF

Author : Maurice Roy
Publisher : Unknown
Page : 722 pages
File Size : 53,6 Mb
Release : 1950
Category : Aeronautics
ISBN : STANFORD:36105024833951

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Theoretical Investigations on the Efficiency and the Conditions for the Realization of Jet Engines by Maurice Roy Pdf

This document covers the topic of propulsion systems that include rocket propulsion and jet propulsion, including some gas turbine material.

Experimental and Theoretical Investigations of the Physical Processes Related to the Retention Capability of a Double Screen Element against Liquid Hydrogen in Earth's Gravity and in Microgravity with Respect to the Applied Stimuli

André Pingel
Experimental and Theoretical Investigations of the Physical Processes Related to the Retention Capability of a Double Screen Element against Liquid Hydrogen in Earth s Gravity and in Microgravity with Respect to the Applied Stimuli Book PDF

Author : André Pingel
Publisher : Cuvillier Verlag
Page : 400 pages
File Size : 43,9 Mb
Release : 2022-08-04
Category : Technology & Engineering
ISBN : 9783736966420

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Experimental and Theoretical Investigations of the Physical Processes Related to the Retention Capability of a Double Screen Element against Liquid Hydrogen in Earth's Gravity and in Microgravity with Respect to the Applied Stimuli by André Pingel Pdf

Metal screens are commonly used as components for fluid handling in spacecraft and rocket tank designs. In most cases, the screens perform a passive separation of the propellant phases. The separation of the liquid from the gaseous propellant phase, is a special challenge. Liquid-gas phase separation means that the gaseous phase is allowed to enter a phase separation device while the liquid phase is blocked. The technical application of this process is the depressurization in a propellant tank. A certain amount of the gaseous propellant phase is vented from the tank through the gas port. The liquid propellant phase remains in the tank in order to be stored for the engine. However, if the tank causes a liquid movement during the depressurization, a part of the liquid can potentially enter the gas port. In order to prevent the unwanted liquid outflow, a separation of the liquid from the gas is necessary. This is possible with the aid of a double screen element and has already been performed for storable liquids in Earth’s gravity and microgravity as well as for cryogenic liquids in Earth’s gravity. At the current state of the art, the separation of the liquid from the gaseous phase of the cryogenic propellant hydrogen using a double screen element has not been performed in microgravity. However, with regard to a possible application, it is mandatory to investigate the function of the double screen element for the real propellant under relevant environmental conditions. In this work, a cryogenic test facility has been developed and operated successfully under Earth’s gravity and microgravity conditions using the drop tower at the University of Bremen. Hereby, the original, cryogenic propellant phases: liquid and gaseous hydrogen, have been used. The experiments show the appearance of the physical processes which are related to the retention capability of a double screen element against liquid hydrogen. Furthermore, these physical processes can obviously be influenced by an unknown boundary condition at the screens: the screen saturation. This unknown boundary condition in turn can obviously be influenced by a certain stimulus which causes a special, fluid mechanical process. A simplified mathematical and two numerical models have been developed which combine the observed, physical processes in the experiments. Two fitting parameters are introduced which influence the flow through screen pressure loss of the liquid and the gaseous hydrogen phase. After the fitting to experimental data, the two fitting parameters have been interpreted with respect to a possible screen saturation. The results lead to a prediction of the unknown boundary condition and indicate that a partial saturation of the screens with liquid could be present in each considered experiment. This can possibly lead to a major influence of the overall resistance of the double screen element against liquid hydrogen.

Experimental and Theoretical Investigations of Steel-Fibrous Concrete

Jacek Tejchman,Jan Kozicki
Experimental and Theoretical Investigations of Steel Fibrous Concrete Book PDF

Author : Jacek Tejchman,Jan Kozicki
Publisher : Springer Science & Business Media
Page : 280 pages
File Size : 46,6 Mb
Release : 2010-10-01
Category : Science
ISBN : 9783642146039

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Experimental and Theoretical Investigations of Steel-Fibrous Concrete by Jacek Tejchman,Jan Kozicki Pdf

Concrete is still the most widely used construction material since it has the lowest ratio between cost and strength as compared to other available materials. However, it has two undesirable properties, namely: low tensile strength and large brittleness that cause the collapse to occur shortly after the formation of the first crack. To improve these two negative properties and to achieve a partial substitute of conventional reinforcement, an addition of short discontinuous randomly oriented steel fibres can be practiced among others. In spite of positive properties, fibrous concrete did not find such acknowledgment and application as usual concrete. There do not still exist consistent dimensioning rules due to the lack sufficient large-scale static and dynamic experiments taking into account the effect of the fibre orientation. The intention of the book is twofold: first to summarize the most important mechanical and physical properties of steel-fibre-added concrete and reinforced concrete on the basis of numerous experiments described in the scientific literature, and second to describe a quasi-static fracture process at meso-scale both in plain concrete and fibrous concrete using a novel discrete lattice model. In 2D and 3D simulations of fibrous concrete specimens under uniaxial tension, the effect of the fibre volume, fibre distribution, fibre orientation, fibre length, fibrous bond strength and specimen size on both the stress-strain curve and fracture process was carefully analyzed.

Report on Certain Experimental and Theoretical Investigations Relative to the Quality, Form, and Combination of Materials for Defensive Armor, Together with Incidental Facts Relative to Their Use for Industrial Purposes

William Rice King
Report on Certain Experimental and Theoretical Investigations Relative to the Quality Form and Combination of Materials for Defensive Armor Together with Incidental Facts Relative to Their Use for Industrial Purposes Book PDF

Author : William Rice King
Publisher : Unknown
Page : 210 pages
File Size : 40,9 Mb
Release : 1870
Category : Armor-plate
ISBN : IBNR:CR100436961

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Report on Certain Experimental and Theoretical Investigations Relative to the Quality, Form, and Combination of Materials for Defensive Armor, Together with Incidental Facts Relative to Their Use for Industrial Purposes by William Rice King Pdf

Theoretical Investigation and Application of Transonic Similarity Law for Two Dimensional Flow

William Perl,Milton M. Klein
Theoretical Investigation and Application of Transonic Similarity Law for Two Dimensional Flow Book PDF

Author : William Perl,Milton M. Klein
Publisher : Unknown
Page : 724 pages
File Size : 55,7 Mb
Release : 1950
Category : Air flow
ISBN : STANFORD:36105024796059

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Theoretical Investigation and Application of Transonic Similarity Law for Two Dimensional Flow by William Perl,Milton M. Klein Pdf

The transonic similarity law for two-dimensional flow derived by von Karman was investigated by an iteration procedure similar to that of the Rayleigh-Janzen and Ackeret-Prandtl-Glauert methods. The results, which show that the potential can be expressed as a power series in a single parameter that depends on Mach number, thickness ratio, and ratio of specific heats, are in agreement with those of von Karman. By the iteration procedure, the second approximation for the flow past a Kaplan section was obtained in similarity form. The exact solution by Kaplan for the second approximation was examined and found expressible in the same similarity form. The exact numerical results to three approximations obtained by Kaplan for the Kaplan section and the circular arc have been reduced to transonic similarity form.

A Theoretical Investigation of the Aerodynamics of Wing-tail Combinations Performing Time-dependent Motions at Supersonic Speeds

John C. Martin,Margaret S. Diederich,Percy J. Bobbitt
A Theoretical Investigation of the Aerodynamics of Wing tail Combinations Performing Time dependent Motions at Supersonic Speeds Book PDF

Author : John C. Martin,Margaret S. Diederich,Percy J. Bobbitt
Publisher : Unknown
Page : 720 pages
File Size : 54,8 Mb
Release : 1954
Category : Aerodynamics, Supersonic
ISBN : STANFORD:36105024831682

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A Theoretical Investigation of the Aerodynamics of Wing-tail Combinations Performing Time-dependent Motions at Supersonic Speeds by John C. Martin,Margaret S. Diederich,Percy J. Bobbitt Pdf

A theoretical investigation is presented of the contribution of horizontal tails to the lift and pitching moment due to angle of attack, a constant rate of pitch, and a constant vertical acceleration. Numerical values of the aerodynamic coefficients associated with these motions are presented for a number of two-dimensional wing-tail combinations, a triangular wing-tail combination, and a number of rectangular-wing - triangular-tail combinations.

Theoretical Investigations of R-F Induction Heated Plasmas

Arthur E. Mensing,Laurence R. Boedeker
Theoretical Investigations of R F Induction Heated Plasmas Book PDF

Author : Arthur E. Mensing,Laurence R. Boedeker
Publisher : Unknown
Page : 90 pages
File Size : 54,6 Mb
Release : 1969
Category : Argon
ISBN : UIUC:30112106856385

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Theoretical Investigations of R-F Induction Heated Plasmas by Arthur E. Mensing,Laurence R. Boedeker Pdf

Outline of Theoretical Psychology

Thomas Teo
Outline of Theoretical Psychology Book PDF

Author : Thomas Teo
Publisher : Springer
Page : 316 pages
File Size : 46,9 Mb
Release : 2018-05-08
Category : Psychology
ISBN : 9781137596512

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Outline of Theoretical Psychology by Thomas Teo Pdf

Outline of Theoretical Psychology discusses basic philosophical problems in the discipline and profession of psychology. The author addresses such topics as what it means to be human in psychology; how psychological knowledge is possible and what it consists of; the role of social justice in psychology; and how aesthetic experience could help us to understand the human condition. Proposing possible solutions to a range of such issues, Thomas Teo situates theoretical questions within traditional branches of philosophical inquiry: ontology, epistemology, ethics, and aesthetics. This book argues that in order to improve psychology as a discipline and in practice, psychologists must reconceive the unit of psychological analysis, looking beyond individual capacity and even experience. By engaging with these basic philosophical problems, Teo demonstrates how psychology can avoid its common pitfalls and continue as a force for resistance and the good.

Theoretical Investigations

Gerry Stahl
Theoretical Investigations Book PDF

Author : Gerry Stahl
Publisher : Springer
Page : 597 pages
File Size : 42,9 Mb
Release : 2022-05-08
Category : Education
ISBN : 3030491595

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Theoretical Investigations by Gerry Stahl Pdf

Computers have transformed how we think, discuss and learn—as individuals, in groups, within cultures and globally. However, social media are problematic, fostering flaming, culture wars and fake news. This volume presents an alternative paradigm for computer support of group thinking, collaborative learning and joint knowledge construction. This requires expanding concepts of cognition to collectivities, like collaborative groups of networked students. Theoretical Investigations explores the conditions for group cognition, supplying a philosophical foundation for new models of pedagogy and methods to analyze group interaction. Twenty-five self-contained investigations document progress in research on computer-supported collaborative learning (CSCL)—both in Stahl’s own research and during the first decade of the CSCL journal. The volume begins with two new reflections on the vision and theory that result from this research. Representing both ethnomethodological and social-constructivist research paradigms, the investigations within this volume comprise a selection of seminal and influential articles and critical commentaries that contribute to an understanding of concepts and themes central to the CSCL field. The book elaborates an innovative theory of group cognition and substantiates the pedagogical potential of CSCL. Theoretical Investigations: Philosophical Foundations of Group Cognition is essential as a graduate text for courses in educational theory, instructional design, learning and networked technologies. The investigations will also appeal to researchers and practitioners in those areas.

Theoretical and Experimental Investigation of the Subsonic-flow Fields Beneath Swept and Unswept Wings with Tails of Vortex-induced Velocities

William J. Alford
Theoretical and Experimental Investigation of the Subsonic flow Fields Beneath Swept and Unswept Wings with Tails of Vortex induced Velocities Book PDF

Author : William J. Alford
Publisher : Unknown
Page : 100 pages
File Size : 47,8 Mb
Release : 1956
Category : Air flow
ISBN : UOM:39015086414441

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Theoretical and Experimental Investigation of the Subsonic-flow Fields Beneath Swept and Unswept Wings with Tails of Vortex-induced Velocities by William J. Alford Pdf

The flow-field characteristics beneath swept and unswept wings as determined by potential-flow theory are compared with the experimentally determined flow fields beneath swept and unswept wing-fuselage combinations. The potential-flow theory utilized considered both the spanwise and chordwise distributions of vorticity as well as the wing-thickness effects. The perturbation velocities induced by a unit horseshoe vortex are included in tabular form.