1,158 research outputs found
Light Quark Masses with Wilson Fermions
We present new data on the mass of the light and strange quarks from
SESAM/TL. The results were obtained on lattice-volumes of
and points, with the possibility to investigate finite-size
effects. Since the SESAM/TL ensembles at have been
complemented by configurations with , moreover, we are now able to
attempt the continuum extrapolation (CE) of the quark masses with standard
Wilson fermions.Comment: Lattice2001(spectrum), minor correction
Monte Carlo Quasi-Heatbath by approximate inversion
When sampling the distribution P(phi) ~ exp(-|A phi|^2), a global heatbath
normally proceeds by solving the linear system A phi = eta, where eta is a
normal Gaussian vector, exactly. This paper shows how to preserve the
distribution P(phi) while solving the linear system with arbitrarily low
accuracy. Generalizations are presented.Comment: 10 pages, 1 figure; typos corrected, reference added; version to
appear in Phys. Rev.
New Results From Lattice QCD: Non-Perturbative Renormalization and Quark Masses
For the first time, we compute non-perturbatively, i.e. without lattice
perturbation theory, the renormalization constants of two-fermion operators in
the quenched approximation at , 6.2 and 6.4 using the Wilson and the
tree-level improved SW-Clover actions. We apply these renormalization constants
to fully non-perturbatively estimate quark masses in the scheme from
lattice simulations of both the hadron spectrum and the Axial Ward Identity in
the quenched approximation. Some very preliminary unquenched Wilson results
obtained from the gluon configurations generated by the TL Collaboration
at and are also discussed.Comment: 4 pages, 2 figures. Invited talk given at the QCD 98 Euroconference,
Montpellier, France, 2-8 July 199
Dynamic models for a heat-led organic rankine cycle
Drawn by the benefits of de-centralised and renewable power supply, over 150 Organic Rankine Cycles (ORC), in a range from 400kWel to 2MWel, have been installed in Central Europe. The majority of modules are biomass fired and heat-led by district heating networks. With rising fuel prices however, the economic situation has become critical for many of these facilities and improvements in efficiency are indispensable. The research reported here, provides turbine models to simulate units of that type and suggests recommendations to achieve a higher cycle efficiency. An operating power plant with a design power of 1MWel serves as validation
Language between intentions and conventions
Titelblatt und Inhaltsverzeichnis
Voranalytisches
Die sprachliche Handlung
Das Meinen
Zwischen Meinen und Verstehen: Die Ă„uĂźerung
Das Verstehen
Im Netzwerk des Gebrauches: Bedeutungszirkulation
Nachanalytisches
LiteraturverzeichnisIn der Sprachphilosophie ist eine der zentralen Fragen, was sprachliche Be-
deutung ist. Damit verbunden ist die Frage wie Sprache funktioniert, ob es die
Sprache ist, die funktioniert oder nicht vielmehr, die Kommunikation, das
aktive Kommunizieren, die In-Gebrauch-Nahme der Sprache, in welche die
sprachliche Bedeutsamkeit gleichsam eingebettet zu sein scheint. Das
Dissertationsprojekt Ăśber Bedeutung. Sprache zwischen Intentionen und
Konventionen beschäftigt sich mit eben diesen Fragen, indem es ver-sucht,
zwischen intentionalistischen und konventionalistischen Ansätzen zur Erklärung
sprachlicher Bedeutung eine BrĂĽcke zu schlagen. Damit ist die Arbeit bereits
in eine bestimmte Debatte um konventionalistische und intentionalistische
Sprachauffassungen eingefasst. Sie verfolgt also nicht die Absicht, zu
erklären, was sprachliche Bedeutung ist, sondern wie man sie innerhalb dieser
Debatte positionieren könnte. Die Kernanalysen der Arbeit betreffen die
Begrifflichkeiten des Meinens und des Verstehens. Um diese zu bearbeiten wird
ein Modell der Bedeutungstrias konzipiert, welches sich zwischen
Sprecherintentionen und Sprachkonven-tionen situiert und die Phänomene des
Meinens und des Verstehens ablichten möchte. An die Stelle der Bedeutung tritt
eine Bedeutungstrias von Sprecher-, Äußerungs- und Hörerbedeutung, welche die
unterschiedlichen und temporären Verdichtungen eines Zirkulationsprozesses
sprachlicher Bedeutung innerhalb interaktiver Kommunikationssituationen
beschreibt. Um das Modell der Bedeutungstrias aufzuspannen, wird eine Debatte
inner-halb der Philosophie der normalen Sprache untersucht, welche sich auf
den Sprechakt als Elementareinheit sprachlicher Kommunikation beruft und in
der sprachliche Bedeutung zwischen den beiden Polen des Intentionalismus und
des Konventionalismus diskutiert wird. Zentral fĂĽr das Dissertations-projekt
sind die Autoren Grice, Searle und Savigny, welche in einer Synthese die
Eckpunkte des Modells der Bedeutungstrias markieren werden. Es stellt sich die
Frage, was in einem Kommunikationsmoment geschieht, in dem ein Sprecher etwas
meint und ein Hörer dieses versteht. Bei der Beant-wortung der Frage wird mit
einem sprechakttheoretischen Begriff sprachli-cher Bedeutung argumentiert,
verstanden als ein propositionaler Gehalt, der durch Regeln und Konventionen
in lexikalischen Einheiten abgefasst wird, phonetisch realisiert wird, und vor
dem Horizont der Interaktion in einen intentionalen Prozess des Meinens gerät,
der in einem Verstehen eben jenes Meinens mĂĽndet. Dieser noch statisch
anmutende Begriff sprachlicher Be-deutung soll durch das sich aufspannende
Modell der Bedeutungstrias zu-sehends dynamisiert werden. Innerhalb der
Kommunikation, in der es zu einer In-Gebrauch-Nahme der Sprache kommt,
verzahnen sich systematische und interaktive Aspekte auf eine so enge und
subtile Weise, dass die Frage nach Sprache als System oder Handlung nicht
gestellt werden kann. Das System dynamisiert sich in der Praxis eines Meinens
und Verstehens, gerät in den Fluss des Interagierens und verliert dort
jegliche feste, universale Kontur. Der Vorgang des Kommu-nizierens dargestellt
im Modell der Bedeutungstrias macht eine Ortung der sprachlichen Bedeutung
schließlich unmöglich. Allerdings ist Sprache als ein Fundus an
regelorientierten und konventionalen Musteranwendungen, auch wenn
Kommunikation jenseits davon existieren kann, dennoch eine operativ wirksame
Fiktion.A central question in the philosophy of language concerns the nature of lin-
guistic meaning. This question introduces the uncertainty about how lan-guage
functions, and whether it is language that functions and not rather
communication, the act of communicating, the usage of language in which
meaning happens. The thesis About Meaning. Language between Intentions and
Conventions treats these questions and attempts to bridge the gap between
intentional and conventional approaches to the explanation of linguistic
meaning. The thesis is embedded in the approach of speech act theory and its
effort to ex-plain linguistic meaning as far as it concerns speaker intentions
and conven-tions. It is not the aim of this project to explain what linguistic
meaning is but to explain how it is to be positioned in this debate. The
central analysis of the thesis concerns the concepts of meaning and un-
derstanding. To deal with these concepts a model is designed which con-cerns
the trias of meaning situated between speaker intentions and linguis-tic
conventions, to define the concepts to mean and to understand. Instead of
meaning, the trias of meaning implies speaker, hearer and utterance mean-ing,
which portray the different and temporal condensations of a circulating
process of linguistic meaning within interactive situations of communication.
To demonstrate the model of the trias of meaning a debate within ordinary
language philosophy is analysed. The speech act is seen as the fundamental
unit of linguistic communication and meaning is discussed between the poles of
intentionalism and conventionalism. The central philosophers dis-cussed are
Grice, Searle and Savigny which mark in a synthesis the three edges of the
model of the trias of meaning. The question addressed is, what exactly happens
in the moment of commu-nication, in which a speaker means something and a
hearer understands the intended meaning. To answer this question the concept
of linguistic meaning in accord with speech act theory is assumed, where
linguistic meaning is a propositional content, formed in lexical units which
follow rules and conven-tions, uttered in phonetical units, and which becomes,
in interaction with the process of meaning, something intended to be
understood by an ad-dressee. This more static concept of linguistic meaning
shall becomes dy-namic under the model of the trias of meaning which points
out the circulat-ing process of meaning and understanding. Within
communication where language is used, systematic and interactive aspects
become interlocked so that questions such as whether language is a system or
an action cannot be answered. The system of language flows within the dynamic
of the practice of meaning and understanding, and en-ters in a state of flux
of interaction where it loses its solid, universal outline. Communication seen
with reference to the model of the trias of meaning makes it impossible to
find the linguistic meaning. However language as a store of rule-governed and
conventional sample applications is an operative effective fiction, albeit
with communication existing beyond
Constructing Improved Overlap Fermions in QCD
We describe an explicit construction of approximate Ginsparg-Wilson fermions
for QCD. We use ingredients of perfect action origin, and further elements. The
spectrum of the lattice Dirac operator reveals the quality of the
approximation. We focus on beta =6 for optimisation. Such fermions are intended
to be inserted into the overlap formula. Hence we also test the speed of
convergence under polynomial evaluation of the overlap formula.Comment: 5 pages, poster presented at Lattice 2000 (Improvement and
Renormalisation
Recent Lattice QCD Results from the UKQCD Collaboration
The lattice technique of studying the strong interaction of matter is used to
obtain predictions of the hadronic spectrum. These simulations were performed
by the UKQCD collaboration using full (unquenched) QCD. Details of the results,
a comparison with quenched data, and novel methods of extracting spectral
properties are described.Comment: Paper presented at the Computational Physics Conference CCP2000, 3-8
Decmeber 2000, Gold Coast, Australia, 5 pages, 3 figure
Heuristic optimization of clusters of heat pumps: A simulation and case study of residential frequency reserve
The technological challenges of adapting energy systems to the addition of more renewables are intricately interrelated with the ways in which markets incentivize their development and deployment. Households with own onsite distributed generation augmented by electrical and thermal storage capacities (prosumers), can adjust energy use based on the current needs of the electricity grid. Heat pumps, as an established technology for enhancing energy efficiency, are increasingly seen as having potential for shifting electricity use and contributing to Demand Response (DR).
Using a model developed and validated with monitoring data of a household in a plus-energy neighborhood in southern Germany, the technical and financial viability of utilizing household heat pumps to provide power in the market for Frequency Restoration Reserve (FRR) are studied. The research aims to evaluate the flexible electrical load offered by a cluster of buildings whose heat pumps are activated depending on selected rule-based participation strategies.
Given the prevailing prices for FRR in Germany, the modelled cluster was unable to reduce overall electricity costs and thus was unable to show that DR participation as a cluster with the heat pumps is financially viable. Five strategies that differed in the respective contractual requirements that would need to be agreed upon between the cluster manager and the aggregator were studied. The relatively high degree of flexibility necessary for the heat pumps to participate in FRR activations could be provided to varying extents in all strategies, but the minimum running time of the heat pumps turned out to be the primary limiting physical (and financial) factor. The frequency, price and duration of the activation calls from the FRR are also vital to compensate the increase of the heat pumps’ energy use. With respect to thermal comfort and self-sufficiency constraints, the buildings were only able to accept up to 34% of the activation calls while remaining within set comfort parameters. This, however, also depends on the characteristics of the buildings. Finally, a sensitivity analysis showed that if the FRR market changed and the energy prices were more advantageous, the proposed approaches could become financially viable. This work suggests the need for further study of the role of heat pumps in flexibility markets and research questions concerning the aggregation of local clusters of such flexible technologies.Comisión Europea 69596
Fluid stability in large scale ORCs using siloxanes: long-term experiences and fluid recycling
The results in this work show the influence of long-term operation on the decomposition of working fluids
in eight different power plants (both heat-led and electricity-led) in a range of 900 kWel to 2 MWel. All
case study plants are using Octamethyltrisiloxane (MDM) as a working fluid. The case study plants are
between six to 12 years old. On one system detailed analyses, including the fluid distribution throughout
the cycle, have been conducted. All fluid samples have been analysed via Head Space Gas Chromatography
Mass Spectrometry (HS-GC-MS). Besides the siloxane composition, the influence of contaminants
such as mineral oil based lubricants (and its components) has been examined. In most cases the original
main working fluid has degraded to fractions of siloxanes with a lower boiling point (low-boilers)
and fractions with a higher boiling point (high-boilers). As a consequence of the analyses, a new fluid
management system has been designed and tested in one case study plant (case study number 8). The
measures include fluid separation, cleansing and recycling.
Pre-post comparisons of fluid samples have proved the effectiveness of the methods. The results show
that the recovery of used working fluid offers an alternative to the purchase of fresh fluid, since operating
costs can be significantly reduced. For large facilities the prices for new fluid range from e15 per
litre (in 2006) to e22 per litre (in 2013), which is a large reinvestment, especially in the light of filling
volumes of 4000 litres to 7000 litres per cycle. With the above mentioned method a price of e8 per litre
of recovered MDM can be achieved
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