Light Quark Masses with Nf=2N_f=2 Wilson Fermions

We present new data on the mass of the light and strange quarks from SESAM/T$\chi$L. The results were obtained on lattice-volumes of $16^3\times 32$ and $24^3\times 40$ points, with the possibility to investigate finite-size effects. Since the SESAM/T$\chi$L ensembles at $\beta=5.6$ have been complemented by configurations with $\beta=5.5$, 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 $\beta=6.0$, 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 $\bar{MS}$ 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 T$\chi$L Collaboration at $\beta=5.6$ and $N_{f}=2$ 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 Äußerung 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 Über 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 Brücke 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 für 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 mündet. 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