618 research outputs found
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Macroscopic implications from phase space dynamics of tokamak turbulence : relaxation, transport, and flow generation
No full textAspects of the macroscopic phenomenology of tokamak plasmas - relaxation, transport, and flow generation - are analyzed in the context of phase space dynamics. Particular problems of interest are: i) fluctuation entropy evolution with turbulence driven flows and its application to flow generation by heat flux driven turbulence, and ii) dynamical coupling between phase space structures and zonal flows and its implication for macroscopic relaxation and transport. In chapter 2, intrinsic toroidal rotation drive by heat flux driven turbulence in tokamak is analyzed based on phase space dynamics. In particular, the dynamics of fluctuation entropy with turbulence driven flows is formulated. The entropy budget is utilized to quantify tokamaks as a heat engine system, where heat flux is converted to macroscopic flows. Efficiency of the flow generation process is defined as the ratio of entropy destruction via flow generation to entropy production via heat input. Comparison of the results to experimental scaling is discussed as well. In chapter 3, dynamics of a single phase space structure (drift hole) is discussed for a strongly magnetized 3D plasma. The drift hole is shown to be dynamically coupled to zonal flows by polarization charge scattering. The coupled dynamics of the drift hole and zonal flow is formulated based on momentum budget. As an application, a bound on the self-bound drift hole potential amplitude is derived. The results show that zonal flow damping appears as a controlling parameter. In chapter 4, dynamics of both a single structure and multi- structures in phase space are discussed for a relevant system, i.e. trapped ion driven ion temperature gradient turbulence. The structures are dynamically coupled to zonal flows, since they must scatter polarization charge to satisfy the quasi-neutrality. The coupled evolution of the structures and flows is formulated as a momentum theorem. An implication for transport process is discussed as well. The transport flux is prescribed by dynamical friction exerted by structures on flows. The dynamical friction exerted by zonal flow is a novel effect and reduces transport by algebraically competing against other fluxes, such as a quasilinear diffusive flu
Women\u27s Cultural Education and Occupation in Serial Novels in the Early Showa Period : Focusing on Mother by Turumi Yusuke(1929)
No full textThis paper examines how the norm of good wife and wise mother was discussed through the usage of the word “educated” in Yusuke Tsurumi’s Mother, serialized in Fujin Club from May 1927 to June 1929. The Fujin Club, started in 1920 by Dai Nippon Yubenkai Kodansha, was a magazine read by many working women and girl students in their early teens to their early twenties. Through collaboration between Seiji Noma, president of Kodansha, who tried to present the mother as an ideal female figure, and author and politician Yusuke Tsurumi, the series Mother was started. It can be considered that Asako, the leading character of Mother, who overcomes various crises in life through ideal education obtained through reading and school, could garner the empathy of the women of those times who dreamt of being independent. However, since success as a working woman was for the progressive future of her son, Asako’s success ultimately gets attributed to the norm of good wife and wise mother. However, rather than seeing the series Mother of the Fujin Club as propaganda, the author would like to consider the significance of the series to lie in its potential as a text through which the Kodansha culture, considered a symbol of anti-cultural education strategically utilized the masses’desire for cultural education.査読研究論文Refereed Paper
Correction: Efficient oxygen evolution on mesoporous IrOx nanosheets (Catalysis Science and Technology (2019) DOI: 10.1039/c9cy00302a)
No full textThe spelling of the name of author Yusuke Yamauchi was incorrect in the original manuscript. The correct spelling is listed as shown above. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers
Collisionless Dynamical Friction and Relaxation in a Simple Drift Wave-Zonal Flow Turbulence
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Taming jets in magnetised fluids
No full textThe effects of a uniform horizontal magnetic field on jets dynamics in 2D Boussinesq turbulence, i.e. Howard-Krishnamurti problem are studied with a numerical simulation. For a fixed fluid and magnetic diffusivity, it is shown that as the imposed field strength becomes larger jets start behaving in a more organized way, i.e. achieve stationary state and are finally quenched. The time evolution of total stress, Reynolds stress, Maxwell stress is examined and all the stresses are shown to vanish when jets are quenched. The quenching of jets is confirmed for different values of magnetic diffusivity, albeit the required field strength increases. It is also shown that the inclusion of overstable modes reinforces jets where Maxwell stress overcomes Reynolds stress. For a larger imposed field jets are shown to quench. A possible mechanism for the transition to the reinforcement of jets by Maxwell stress is discussed based on the transition in the most unstable mode in the underlying turbulence
Collisionless Dynamical Friction and Relaxation in a Simple Drift Wave-Zonal Flow Turbulence
No full textBlob-Hole Structures as Non-Axisymmetric Equilibrium Solutions for Potential Vorticity Conserving Fluids
No full textDeriving safety constraints for integration of unmanned aircraft systems into the national airspace by application of STECA
No full textThesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, Technology and Policy Program, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 129-132).Unmanned aircraft systems (UAS) have been used for years especially in the military. However, the operation of UAS in civil aviation has been limited since there are a lot of uncertainties: a regulatory scheme needs to be established and associated technologies need to be developed. This thesis contributes to both technology development and establishing a regulatory scheme for UAS by generating safety constraints using the new methodology developed by Professor Leveson and Dr. Fleming. This methodology is called "'Systems-Theoretic Early Concept Analysis" (STECA) and is based on Systems-Theoretic Accident Model and Processes (STAMP) analysis, which is also developed by the professor. STECA has potential to generate more safety constraints that have not been considered otherwise in the early stage of development and this allows the producer to redesign the entire system with potentially less cost. This thesis illustrates why and how STECA can be powerful to support integration of UAS into NAS. In addition, this thesis actually demonstrates how STECA derives safety constraints as a case study and shows how the safety constraints should be integrated in the system development.by Yusuke Urano.S.M. in Technology and Polic
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