931 research outputs found
Confinement in three-dimensional magnetic monopole–dipole gas
No full textAbstractConfinement of electrically charged test particles in the dilute plasma of monopoles and pointlike magnetic dipoles is studied. We calculate the tension of the string emerging between the infinitely separated test particles. The string tension is an increasing function of the dipole density provided other parameters of the plasma are fixed. The relevance of our results to confining gauge theories is discussed
Gebiedsontwikkeling na(ast) zware industriële bedrijvigheid
No full textIn deze bijdrage staan vraagstukken die zich voordoen rondom gebiedsontwikkeling in de nabijheid van zware industrie centraal. Vanuit juridisch en bestuurskundig oogpunt wordt ingegaan op de mogelijkheden tot (het afdwingen van) 'vergroening' van de industrie en/of de keuzes tot behoud, tot verplaatsing of stopzetten van de industriële activiteiten en wie daarover besluit. Auteurs laten zien dat verschillende rationaliteiten elk met eigen spelers, instrumenten en argumenten de toekomst van het gebied benaderen.Urban Development ManagementManagement in the Built Environmen
Embedded topological defects in hot electroweak theory: a lattice study
No full textChernodub MN, Gubarev FV, Ilgenfritz E-M, Schiller A. Embedded topological defects in hot electroweak theory: a lattice study. Physics Letters B. 1998;434(1-2):83-91.We study the properties of Nambu monopoles and Z-vortices in the 3D lattice SU(2) Higgs theory which represents the Standard Model at high temperature. We show that the densities of the Nambu monopoles and the Z-vortices are O(1) in the symmetric phase and generically small in the Higgs phase. Near to the critical Higgs mass and in the vicinity of the phase transition the densities are no more negligible in the broken phase. The percolation probability of the Z-vortex lines is found as a new disorder parameter for this phase transition. We conclude that the transition to the symmetric phase is accompanied by Z-vortex condensation. Simulations comparing elementary and extended vortices and monopoles at different beta(G) values, aiming to show that the density of vortices and monopoles of fixed physical size might have a well-defined continuum limit, gives encouraging but so far inconclusive results. (C) 1998 Published by Elsevier Science B.V. All rights reserved
M.N. Roy's Critique of Marxist Tradition: Revisiting and Appropriation of the Notion of Freedom in Radical Humanism for Development Ethics
No full textIn this paper the author aims to explore the philosophy of
one o f the modem atheistic philosopher’s of India, M.N. Roy to find
out how he critiqued and re-interpreted the tradition that he came
from, i. e., Marxism, and to develop his own system, namely, Radi-
cal Humanism. It further dwells on its key concepts o f freedom,
rationality and morality to finds their relevance for a secular devel-
opment ethics. For this, according to the author, we need to look for
philosophies and world-views that would put us on the right path
living for all. While so much has been written about the role of
religion to orient ourselves for a holistic future, the author holds
that M.N. Roy’s radical humanism provides an alternative world
view from which all irrespective o f religious creeds and ideological
colours can draw inspiration and motivations for a holistic environ
mental ethics
Structure and dynamics of turbulent flows over highly permeable walls
No full textHighly porous materials are found in various industrial applications and environmental flows. In previous studies it was found that a turbulent flow along a highly porous wall experiences a higher skin friction as compared to a solid wall with similar surface roughness when the so-called permeability Reynolds number (Re_K) is larger than O(1). The main objective of the present study was to gain understanding of the characteristic structures and auto-generation mechanisms of turbulence for Re_K >> 1. To this purpose the Volume-Averaged Navier-Stokes (VANS) equations were solved in a Direct Numerical Simulation (DNS) of a turbulent flow through a plane channel with an upper solid wall and a lower porous wall at Re_K = 5.91. The DNS results are in good agreement with available Particle Image Velocimetry (PIV) data for the same flow geometry. A linear stochastic estimation technique was used to capture the structure associated with the characteristic ejection event that contributes most to the Reynolds shear stress near the porous wall. This structure is similar to a horseshoe vortex. Contrary to the conventional hairpin vortex found near solid walls, this horseshoe vortex has a significantly higher inclination angle with the wall and its legs are much shorter. The latter is consistent with the observed absence of low and high-speed streaks near highly permeable walls. Next, the auto-generation mechanisms of the horseshoe vortex were studied in another DNS in which the horseshoe vortex was released in the Reynolds-averaged flow field obtained from the former DNS. Two distinct auto-generation mechanisms were observed: (1) the generation of new structures at the upstream end of the horseshoe vortex, which evolve rapidly into a turbulent spot with an arrowhead shape, and (2) the interaction of the horseshoe vortex with spanwise oriented Kelvin-Helmholtz vortex rollers originating from the inflexion point in the mean velocity profile near the porous wall
Het omgevingsrecht in de praktijk van gebiedsontwikkeling; verbinding tussen omgevingsrecht en andere disciplines.: Voorwoord
No full textDe start van de nieuwe leeropdracht Omgevingsrecht in gebiedsontwikkeling aan de TU Delft is aanleiding voor een verkenning van de verbinding tussen het omgevingsrecht en andere disciplines. Dit hoofdstuk bevat een inleiding op de bundel waarin bijdragen zijn opgenomen met een multidisciplinaire blik op een omgevingsvraagstuk. De bijdragen zijn geschreven door duo's van auteurs; een jurist en een beoefenaar van een andere discipline. Samen reflecteren zij op de praktijk, de mogelijkheden van de Omgevingswet en de leerpunten van de multidisciplinaire verkenning. In deze inleiding wordt toegelicht wat wordt bedoeld met multidisciplinariteit en wanneer dit toegevoegde waarde heeft.Urban Development ManagementDesign & Construction ManagementPractice Chair Urban Area Developmen
Preservation for Institutional Repositories: practical and invisible
No full textWith good prospects for growth in institutional repository (IR) contents, in the UK, due to the proposed RCUK policy on mandating deposit of papers on funded work, and internationally due to the Berlin 3 recommendation, it is timely to investigate preservation solutions for IRs. The paper takes a broad view of preservation issues for IRs - based on practice, experience and visions for the future - from the perspective of Preserv, a JISC-funded project. It considers preservation in the context of IRs. Based on the OAIS preservation model, an architecture is proposed to support distributed preservation services for IRs. Work performed so far involves adapting the IR user deposit interface in a pilot version of EPrints software for building IRs, and determining accurate file format information using Pronom software. The paper looks ahead briefly at the role of preservation service providers, working for the IR, within this architecture. The strategy is to take practical steps that are, as far as possible, invisible to all but those concerned with the preservation process for IRs
Effects of random phase and amplitude errors in optical fiber Bragg gratings
No full textThis paper studies the influence of random phase and amplitude fabrication errors on the performance of optical filters based on fiber Bragg gratings (FBGs). In particular, we analyze two effects of particular importance for optical communications: the excess crosstalk induced in apodized gratings commonly used in wavelength-division-multiplexing (WDM) systems, and the time-delay fluctuations that appear in chirped gratings employed to compensate the fiber dispersion. A statistical model is presented to explain these effects in terms of the coherence length of the grating fabrication procedure
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