149,220 research outputs found

    The concept of strong and weak virtual reality

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    We approach the virtual reality phenomenon by studying its relationship to set theory, and we investigate the case where this is done using the wellfoundedness property of sets. Our hypothesis is that non-wellfounded sets (hypersets) give rise to a different quality of virtual reality than do familiar wellfounded sets. We initially provide an alternative approach to virtual reality based on Sommerhoff's idea of first and second order self-awareness; both categories of self-awareness are considered as necessary conditions for consciousness in terms of higher cognitive functions. We then introduce a representation of first and second order self-awareness through sets, and assume that these sets, which we call events, originally form a collection of wellfounded sets. Strong virtual reality characterizes virtual reality environments which have the limited capacity to create only events associated with wellfounded sets. In contrast, the more general concept of weak virtual reality characterizes collections of virtual reality mediated events altogether forming an entirety larger than any collection of wellfounded sets. By giving reference to Aczel's hyperset theory we indicate that this definition is not empty, because hypersets encompass wellfounded sets already. Moreover, we argue that weak virtual reality could be realized in human history through continued progress in computer technology. Finally, we reformulate our characterization into a more general framework, and use Baltag's Structural Theory of Sets (STS) to show that within this general hyperset theory Sommerhoff's first and second order self-awareness as well as both concepts of virtual reality admit a consistent mathematical representation.Comment: 17 pages; several edits in v

    Formal verification of coupling properties for an automotive software integration across XilL

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    Virtualization and desktop testing of an integrated system without inclusion of a physical hardware is a well-established concept due to today’s abundant computing power availability. However, only few aspects of reality are introduced in steps into these virtual environments. The aspects of reality like hard-real time deadlines, timing events, coupling frequency and data synchronization between two subsystems in a system offer complexity without fair estimation of its consequence on the system behavior. In this paper, we describe the abovementioned complexity as the coupling properties detailed for a combustion engine example along with its controller. We formally verify the timing, safety, liveness and deadlock properties of the coupling by modeling them as timed transition systems. The example is verified for the idle speed control, smooth mode switching and for injection cutoff control where the interaction between the subsystems is very critical. The paper highlights a very important perspective of strong and weak subsystem coupling while transiting from Model-in-the-loop (MiL) to Software-in-the-Loop (SiL) and finally to Hardware-in-the-Loop (HiL). In conclusion, the input-output behavior of the coupled subsystems is also presented for a realistic observation of the control loop

    Asymptotic Freedom: From Paradox to Paradigm

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    Asymptotic freedom was developed as a response to two paradoxes: the weirdness of quarks, and in particular their failure to radiate copiously when struck; and the coexistence of special relativity and quantum theory, despite the apparent singularity of quantum field theory. It resolved these paradoxes, and catalyzed the development of several modern paradigms: the hard reality of quarks and gluons, the origin of mass from energy, the simplicity of the early universe, and the power of symmetry as a guide to physical law.Comment: 26 pages, 10 figures. Lecture on receipt of the 2004 Nobel Prize. v2: typo (in Ohm's law) correcte

    Quantum Field Theory

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    I discuss the general principles underlying quantum field theory, and attempt to identify its most profound consequences. The deepest of these consequences result from the infinite number of degrees of freedom invoked to implement locality. I mention a few of its most striking successes, both achieved and prospective. Possible limitations of quantum field theory are viewed in the light of its history.Comment: LaTeX, 12 pages, 3 figures. Will appear in Centenary issue of Rev. of Mod. Phys., March 1999. Incorporated minor corrections suggested by edito

    Fast Magnetic Reconnection and Spontaneous Stochasticity

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    Magnetic field-lines in astrophysical plasmas are expected to be frozen-in at scales larger than the ion gyroradius. The rapid reconnection of magnetic flux structures with dimensions vastly larger than the gyroradius requires a breakdown in the standard Alfv\'en flux-freezing law. We attribute this breakdown to ubiquitous MHD plasma turbulence with power-law scaling ranges of velocity and magnetic energy spectra. Lagrangian particle trajectories in such environments become "spontaneously stochastic", so that infinitely-many magnetic field-lines are advected to each point and must be averaged to obtain the resultant magnetic field. The relative distance between initial magnetic field lines which arrive to the same final point depends upon the properties of two-particle turbulent dispersion. We develop predictions based on the phenomenological Goldreich & Sridhar theory of strong MHD turbulence and on weak MHD turbulence theory. We recover the predictions of the Lazarian & Vishniac theory for the reconnection rate of large-scale magnetic structures. Lazarian & Vishniac also invoked "spontaneous stochasticity", but of the field-lines rather than of the Lagrangian trajectories. More recent theories of fast magnetic reconnection appeal to microscopic plasma processes that lead to additional terms in the generalized Ohm's law, such as the collisionless Hall term. We estimate quantitatively the effect of such processes on the inertial-range turbulence dynamics and find them to be negligible in most astrophysical environments. For example, the predictions of the Lazarian-Vishniac theory are unchanged in Hall MHD turbulence with an extended inertial range, whenever the ion skin depth δi\delta_i is much smaller than the turbulent integral length or injection-scale Li.L_i.Comment: 31 pages, 5 figure

    Using Frustration in the Design of Adaptive Videogames

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    In efforts to attract a wider audience, videogames are beginning to incorporate adaptive gameplay mechanics. Unlike the more traditional videogame, adaptive games can cater the gaming experience to the individual user and not just a particular group of users as with the former. Affective videogames, games that respond to the user's emotional state, may hold the key to creating such gameplay mechanics. In this paper we discus how the emotion frustration may be used in the design of adaptive videogames and the ongoing research into its detection and measurement
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