545 research outputs found
Estimation of the total error of modal wavefront reconstruction with Zernike polynomials and Hartmann-Shack test
No full textThe paper discusses the influence of the Hartmann-(Shack) wavefront sensor geometry on the total error of modal wavefront reconstruction. A mathematical model is proposed which describes modal wavefront reconstruction based on Hartmann or Hartmann-Shack sensor in terms of linear operators. The modal covers the most general case and is not limited by the orthogonality of decomposition basis or by the method chosen for decomposition. The total reconstruction error is calculated for any given statistics of the wavefront to be measured. Based on this estimate, total reconstruction error is calculated for regular and randomised Hartmann masks. The calculations demonstrate that use of random masks with non-regular Fourier spectra for Zernike wavefront reconstruction for atmospheric turbulence allows to double the number of decomposition modes with the same total error.Electronic InstrumentationElectrical Engineering, Mathematics and Computer Scienc
Error estimation and adjoint-based adaptation in aerodynamics
No full textIn this article we give an overview of recent developments
in error estimation and in residual-based and goal-oriented
(adjoint-based) adaptation for Discontinuous Galerkin discretizations
of sub- and supersonic viscous compressible flows. We also give an
outlook on the planned continuation of this research in the EU project
ADIGMA
The Mathematical Foundation of Structural Mechanics
No full textThis book attempts to acquaint engineers who have mastered the essentials of structural mechanics with the mathematical foundation of their science, of structural mechanics of continua. The prerequisites are modest. A good working knowledge of calculus is sufficient. The intent is to develop a consistent and logical framework of theory which will provide a general understanding of how mathematics forms the basis of structural mechanics. Emphasis is placed on a systematic, unifying and rigorous treatment. Acknowledgements The author feels indebted to the engineers Prof. D. Gross, Prof. G. Mehlhorn and Prof. H. G. Schafer (TH Darmstadt) whose financial support allowed him to follow his inclinations and to study mathematics, to Prof. E. Klingbeil and Prof. W. Wendland (TH Darmstadt) for their unceasing effort to achieve the impossible, to teach an engineer mathematics, to the staff of the Department of Civil Engineering at the University of California, Irvine, for their generous hospitality in the academic year 1980-1981, to Prof. R. Szilard (Univ. of Dortmund) for the liberty he granted the author in his daily chores, to Mrs. Thompson (Univ. of Dortmund) and Prof. L. Kollar (Budapest/Univ. of Dortmund) for their help in the preparation of the final draft, to my young colleagues, Dipl.-Ing. S. Pickhardt, Dipl.-Ing. D. Ziesing and Dipl.-Ing. R. Zotemantel for many fruitful discussions, and to cando ing. P. Schopp and Frau Middeldorf for their help in the production of the manuscript. Dortmund, January 1985 Friedel Hartmann Contents Notations ........................................................... XII Introduction .......................................................
On the admissibility of finite groups over semi-global fields in the bad characteristic case
No full textIn the last 20 years, a method of constructing various algebraic objects over semi-global fields by patching together compatible objects constructed on a network of field extensions has been introduced and developed by Harbater, Hartmann, and Krashen. For example, field patching can be used to study central simple algebras and Galois extensions over these fields. This has been a powerful tool in considering the problem of admissibility over these fields. Given a finite group G and a field F we say that G is admissible over F if there is a division algebra central over F with a maximal subfield that is a Galois extension of F with group G. In this thesis we build on their work and results of Guico (2020) to completely characterize admissible groups over function fields of curves over equicharacteristic complete discretely valued fields with algebraically closed residue fields.Ph.D.Includes bibliographical reference
THE ECONOMIC IMPLICATIONS OF CHEMICAL USE RESTRICTIONS IN AGRICULTURE
No full textAgricultural and Food Policy, Crop Production/Industries,
Hot balls dry sludge
No full textEach year some 25 million m3 of mineral sludge are dredged from rivers, canals and harbours in the Netherlands alone, twenty percent of which is polluted. The unpolluted sludge is usually dumped at sea. The remaining five million m3 may only be dumped in a few selected landfill locations, at considerable cost.A sludge flock, hotographed at the DelftLaboratory of Fluid Mechanics. Sludge consists of a collection of small particles, including clay, fine sand, organic material, and a lot of water, and if the dredgings came from anywhere near the sea, silt. The clay particles give sludge its characteristic properties, which differ from, say, sand. The clay particles are cohesive, so when they meet they tend to stick together. The size of a flock varies from a few dozen to many hundreds of micrometers (see also Delft Outlook 2003.2).In the late nineteen-eighties the processing of mineral sludge from soil remediation projects and dredgings was still too costly. So the Slufter, a 260 hectare basin that can hold 150 million cubic metres of sludge, was created at Europoort near Rotterdam. Each year, some 3 to 5 million tons of dredgings are added to the 50 metre deep reservoir.Delft University of Technolog
100 years of "aesthetics from below" [Translated with www.DeepL.com]
No full textAuf der Grundlage des augustischen Dualismus von Erfahrung und Wissen diskutiert dieser Bericht die Geschichte von Fechners "Ästhetik von unten" im Laufe der letzten 100 Jahre. Die britische Aufklärungsphilosophie erweist sich als Quelle dieser empirischen Ästhetiktheorie, ihre gesellschaftspolitische Relevanz zeigt sich am Eifer seiner oft stark parteiischen zeitgenössischen Kritiker wie E. v. Hartmann, F. Brentano und B. Croce. Zu Beginn dieses Jahrhunderts wurde eine außergewöhnliche Anzahl von Experimenten in der ästhetischen Psychologie durchgeführt, aber ihre Ergebnisse boten keine Grundlage für spätere Forschungen zur Formulierung einer überzeugenden Theorie. Nach dem Zweiten Weltkrieg wurde die Forschung auf diesem Gebiet von elementorientierten Theorien (Informationstheorie) beeinflusst, was vom Autor kritisiert wird, der eine Rückkehr zu den Ideen der Gestaltpsychologie empfiehlt. [Translated with www.DeepL.com]Based on the Augustianian dualism of experience and knowledge, this report discusses the history of Fechner's »Ästhetik von unten« in the course of the last 100 years. The British philosophy of enlightenment is shown to be the source of this empiric theory of aesthetics, its socio-political relevance is demonstrated by the fervour of his often strongly biased contemporary critics, such as E. v. Hartmann, F. Brentano and B. Croce. At the beginning of this century an extraordinary number of experiments in aesthetical psychology were made but their results offered no base for later research to formulate a convincing theory. After World War II, research in this field was influenced by element orientated theories (information theory) which is criticized by the author who recommends a return to the ideas of Gestalt psychology.notReviewedpublishedVersio
Investigation of flashing induced instabilities in BWRS: Simulations and experiments
No full textFlashing induced instabilities in a BWR test-facility (CIRCUS) have been investigated. A steady-state model of the thermo-hydraulic behavior of a simplified natural circulation cooled BWR setup has been derived. An asymmetric power distribution in the core leads to asymmetric boifing boundaries in the core and small differences in flow-rate in the core-channels. However, the natural circulation is mainly driven by density differences between the riser section and the downcomer section, keeping the differences in flow-rate small. The time dependent flow-rate in the core-channels has been measured by means of LDA during unstable conditions ofthe CIRCUS facility, a steam-water simulator operating at 1.2 bar. Various asymmetric power distributions (leading to a difference in specific energy at the core exit up to 1 M J / k g ) have been studied under several core inlet temperatures, ranging from 98°C - 102°C. Increasing inlet temperature and total power leads to a destabilizing of CIRCUS at the particular points measured. Increasing asymmetry in power distribution leads to increasing flow-rate differences between the two core channels measured. The steady-state simulations overestimate the experiments, but the trends in flow-rate at increasing inlet temperature and total power are similar.Kramers Laboratorium voor Fysische TechnologieApplied Science
Il "metodo" ontologico e le sue aporie
No full textThe ontological “method” and its aporias. Discussing the book by G. D’Anna
Realismi. Nicolai Hartmann “al di là” di realismo e idealismo (Brescia, 2013), the
author criticizes the methodological approach to ontology. He also claims that the meaning of
the correlation I-world is not merely an epistemological one but an ontological one, defined as
a co-existential relationship. The author finally suggests a possible approach between historicism
and ontology which converges in the idea of “knowledge of reality” founded on Dilthey’s
ganzer Mensch
- …
