Ordered 180 degrees ferroelectric domains in epitaxial submicron structures

Large range ordered La(0.7)Sr(0.3)MnO(3) and SrRuO(3) epitaxial dots were fabricated by pulsed laser deposition using stencil masks and were embedded in ferroelectric PbTiO(3) epitaxial films. PbTiO(3) films grown on top of La(0.7)Sr(0.3)MnO(3) dots form arrays of 180 degrees domains that are switchable and have good ferroelectric properties. PbTiO(3) films made on top of SrRuO(3) dots have a monodomain polarization state. These observations point out the importance of the electronic properties of the bottom electrode in the selection of a preferential polarization state in epitaxial ferroelectric films and propose a route of fabricating large arrays of switchable 180 degrees ferroelectric domains. (C) 2011 American Institute of Physics. [doi:10.1063/1.3630232]

On the numerical solution of the 2d wave equation with compact fdtd schemes

This paper discusses compact-stencil finite difference time domain (FDTD) schemes for approximating the 2D wave equation in the context of digital audio. Stability, accuracy, and efficiency are investigated and new ways of viewing and interpreting the results are discussed. It is shown that if a tight accuracy constraint is applied, implicit schemes outperform explicit schemes. The paper also discusses the relevance to digital waveguide mesh modelling, and highlights the optimally efficient explicit scheme.

On the Benefits of Abstraction in Concurrent Haskell

Heutzutage haben selbst durchschnittliche Computersysteme mehrere unabhängige Recheneinheiten (Kerne). Wird ein rechenintensives Problem in mehrere Teilberechnungen unterteilt, können diese parallel und damit schneller verarbeitet werden. Obwohl die Entwicklung paralleler Programme mittels Abstraktionen vereinfacht werden kann, ist es selbst für Experten anspruchsvoll, effiziente und korrekte Programme zu schreiben. Während traditionelle Programmiersprachen auf einem eher geringen Abstraktionsniveau arbeiten, bieten funktionale Programmiersprachen wie z.B. Haskell, Möglichkeiten zur fortgeschrittenen Abstrahierung. Das Ziel der vorliegenden Dissertation war es, zu untersuchen, wie gut verschiedene Arten der Abstraktion das Programmieren mit Concurrent Haskell unterstützen. Concurrent Haskell ist eine Bibliothek für Haskell, die parallele Programmierung auf Systemen mit gemeinsamem Speicher ermöglicht. Im Mittelpunkt der Dissertation standen zwei Forschungsfragen. Erstens wurden verschiedene Synchronisierungsansätze verglichen, die sich in ihrem Abstraktionsgrad unterscheiden. Zweitens wurde untersucht, wie Abstraktionen verwendet werden können, um die Komplexität der Parallelisierung vor dem Entwickler zu verbergen. Bei dem Vergleich der Synchronisierungsansätze wurden Locks, Compare-and-Swap Operationen und Software Transactional Memory berücksichtigt. Die Ansätze wurden zunächst bezüglich ihrer Eignung für die Synchronisation einer Prioritätenwarteschlange auf Basis von Skiplists untersucht. Anschließend wurden verschiedene Varianten des Taskpool Entwurfsmusters implementiert (globale Taskpools sowie private Taskpools mit und ohne Taskdiebstahl). Zusätzlich wurde für das Entwurfsmuster eine Abstraktionsschicht entwickelt, welche eine einfache Formulierung von Taskpool-basierten Algorithmen erlaubt. Für die Untersuchung der Frage, ob Haskells Abstraktionsmethoden die Komplexität paralleler Programmierung verbergen können, wurden zunächst stencil-basierte Algorithmen betrachtet. Es wurde eine Bibliothek entwickelt, die eine deklarative Beschreibung von stencil-basierten Algorithmen sowie ihre parallele Ausführung erlaubt. Mit Hilfe dieses deklarativen Interfaces wurde die parallele Implementation vollständig vor dem Anwender verborgen. Anschließend wurde eine eingebettete domänenspezifische Sprache (EDSL) für Knoten-basierte Graphalgorithmen sowie eine entsprechende Ausführungsplattform entwickelt. Die Plattform erlaubt die automatische parallele Verarbeitung dieser Algorithmen. Verschiedene Beispiele zeigten, dass die EDSL eine knappe und dennoch verständliche Formulierung von Graphalgorithmen ermöglicht.

A high-order arbitrarily unstructured finite-volume model of the global atmosphere: tests solving the shallow-water equations

Simulations of the global atmosphere for weather and climate forecasting require fast and accurate solutions and so operational models use high-order finite differences on regular structured grids. This precludes the use of local refinement; techniques allowing local refinement are either expensive (eg. high-order finite element techniques) or have reduced accuracy at changes in resolution (eg. unstructured finite-volume with linear differencing). We present solutions of the shallow-water equations for westerly flow over a mid-latitude mountain from a finite-volume model written using OpenFOAM. A second/third-order accurate differencing scheme is applied on arbitrarily unstructured meshes made up of various shapes and refinement patterns. The results are as accurate as equivalent resolution spectral methods. Using lower order differencing reduces accuracy at a refinement pattern which allows errors from refinement of the mountain to accumulate and reduces the global accuracy over a 15 day simulation. We have therefore introduced a scheme which fits a 2D cubic polynomial approximately on a stencil around each cell. Using this scheme means that refinement of the mountain improves the accuracy after a 15 day simulation. This is a more severe test of local mesh refinement for global simulations than has been presented but a realistic test if these techniques are to be used operationally. These efficient, high-order schemes may make it possible for local mesh refinement to be used by weather and climate forecast models.

Ultra High Temperatures #1

Ultra High Temperature #1, initiated by Rebecca Bibby forms the first in an ongoing project which explores the realms of collaboration, performance, writing and publication as artistic vehicle of production, dispersion and progression. With Bibby's text -that re-fictions the futuristic projections of technosexuality in Metropolis (1927)- at its core was launched, printed, compiled and distributed in a live performance by POLLYFIBRE at Eastside Projects in Birmingham. The limited edition printed publication was designed by An Endless Supply whose Risograph stencil printer was used as an instrument in the performed production of the text. As a crude avatar of Rebecca Bibby’s practice, Aikon-II, a mechanically programmed signature machine automatically signed each copy of the text during the performance. POLLYFIBRE's ‘flat-pack’ costumes were on display throughout the duration of the exhibition. POLLYFIBRE is a performance project created by Christine Ellison.

A reconstruction of stencilling based on the description by Gilles Filleau des Billettes

This essay recounts and illustrates the reconstruction and testing of tools, furniture and working methods for stencilling texts. The description on which the reconstruction is based, written by Gilles Filleau des Billettes in Paris in the 1690s, is supplied elsewhere in this volume, together with an English translation. From the reconstruction and tests conducted with it, observations and conclusions are drawn about its effectiveness and its likely relationship to (then) contemporary stencilling practices. Four appendices are also included dealing with Des Billettes's method of designing and spacing letters; the cutting of stencils; the engraving by Louis Simonneau that accompanies Des Billettes's text; and later stencil configurations and working methods that incorporate the same or similar features to those described by Des Billettes.

A tradition with breaks

An introduction to the history of stencil typefaces, followed by a survey of recent stencil typefaces (1990s to the present day) arranged in eight thematic sections.

The description of stencilling by Gilles Filleau des Billettes: transcription and translation

This article presents the description of stencilling by Gilles Filleau des Billettes. The description sets out a method for stencilling letters, words, and texts, and specifies equipment for doing the work; it forms the basis for a reconstruction of the equipment and method, which is presented in a parallel article in this volume of Typography papers (see E. Kindel, 'A reconstruction of stencilling based on the description by Gilles Filleau des Billettes', Typography papers, 9, pp. 28–65). The original French text, approximately 10,000 words in length, is here transcribed and accompanied by a parallel English translation. Introductory notes on the preparation of both texts are provided; images of stencil letters found among the papers of Sébastien Truchet, Des Billettes’s colleague, are shown in an appendix.

Typography papers, 9

This latest issue of the series of Typography papers opens with a beautifully illustrated article by the type designer Gerard Unger on ‘Romanesque’ letters. A further installment of Eric Kindel’s pathbreaking history of stencil letters is published in contributions by him, Fred Smeijers, and James Mosley. Maurice Göldner writes the first history of an early twentieth-century German typefounder, Brüder Butter. William Berkson and Peter Enneson recover the notion of ‘readability’ through a history of the collaboration between Matthew Luckiesh and the Linotype Company. Paul Luna discusses the role of pictures in dictionaries. Titus Nemeth describes a new form of Arabic type for metal composition. The whole gathering shows the remarkable variety and vitality of typography now.

Marked by time

A concise study of two stencil-makers' catalogues published in Germany and the USA in the mid-twentieth century.

ENO adaptive method for solving one-dimensional conservation laws

In this work an efficient third order non-linear finite difference scheme for solving adaptively hyperbolic systems of one-dimensional conservation laws is developed. The method is based oil applying to the solution of the differential equation an interpolating wavelet transform at each time step, generating a multilevel representation for the solution, which is thresholded and a sparse point representation is generated. The numerical fluxes obtained by a Lax-Friedrichs flux splitting are evaluated oil the sparse grid by an essentially non-oscillatory (ENO) approximation, which chooses the locally smoothest stencil among all the possibilities for each point of the sparse grid. The time evolution of the differential operator is done on this sparse representation by a total variation diminishing (TVD) Runge-Kutta method. Four classical examples of initial value problems for the Euler equations of gas dynamics are accurately solved and their sparse solutions are analyzed with respect to the threshold parameters, confirming the efficiency of the wavelet transform as an adaptive grid generation technique. (C) 2008 IMACS. Published by Elsevier B.V. All rights reserved.

Plantering av plantor med frysta substratklumpar

Följande slutsatser kan dras från denna och andras studier vad avser konsekvenser av plantering med frysta substratklumpar: Plantering av plantor vars substrat inte hunnit tina kan under vissa betingelser gå bra medan andra förhållanden speciellt på våren med kalla jordar i kombination med torr och varm väderlek kan orsaka allvarliga plantskador. Generellt kan man räkna med att få en viss nedsättning av plantans fysiologiska status efter plantering med frysta substratklumpar som accentueras under betingelser som stressar plantan. En sådan stress kan vara då plantans substrat tinar långsamt beroende på en stor frusen massa (stora substratklumpar) och vid kalla markförhållanden.

Etablering, tillväxt och skador för plantor odlade i såddrör (Tubesprout™) - resultat efter två säsonger i fält

Försöket visade på mycket god överlevnad för plantor odlade i såddrören, Tubesprout™. Efter två år var överlevnaden för dessa 91 % för tall och 79 % för gran. För miniplantorna odlade i Jiffy varierade överlevnaden efter två år mellan 84 (tall) och 64 % (gran). Lägst överlevnad efter både det första och andra året hade de större referensplantorna. Av dessa levde 67 % av tallplantorna och endast 45 % av granplantorna. Bidragande till den goda överlevelsen hos Tubesprout™-odlade plantor var få snytbaggeskador och nästan inga skador av torka. Det andra miniplantsystemet, Jiffy 18, klarade snytbaggen nästan lika bra som Tubesprout™, men drabbades istället av stora avgångar beroende på torka. Hylsan tycks förhindra uttorkning av plantan som annars är ett stort problem vid plantering på torra marker av små plantor. För de äldre täckrotsodlade referensplantorna var den mesta plantdöden orsakad av kraftiga snytbaggeskador. Granen var värst drabbad med drygt 50 % snytbaggedödade plantor efter två år, medan den plantavgång hos tall som var orsakad av snytbagge var 26 %. Några plantor som stod i Tubesprout™ på försöksytan blev dock uppryckta, sannolikt av kråkfåglar.

Grafismos no projeto Botuáfrica: um diálogo intercultural

This article aims to present the Botuafrica Project and graphism generated by the stencil printing process. We will address the issue of valuing African-Brazilian aesthetics by producing symbols created by the participants of the project and fashion as a vehicle for social inclusion in the context of Botucatu Municipality of state of São Paulo. The study proposes a reflection on the work of professionals that contributed on practices of technical and concept development in order to promote the creation of local fashion and production. This research will verify the implications of act of drawing, printing and wearing the textiles designed by the participants of the project. Botucatu Institute collected and archived photos and drawings during the project between years 2010 and 2012 and provided this material for this research.

La ciudad atravesada : Un análisis de los stencils políticos en los edificios estatales de la ciudad de La Plata

La intención central de este trabajo es, a partir la puesta en relación de algunas de las lentes conceptuales concebidas por autores como Theodor W. Adorno, Roland Barthes, Walter Benjamin, Oscar Steimberg y Eliseo Verón, entre otros, reflexionar sobre los stencils de corte político observados en los edificios estatales [es decir, aquellos ocupados por los Poderes Ejecutivo, Judicial y Legislativo], ubicados en el centro de la ciudad de La Plata como un fenómeno social que puede ser analizado desde la teoría crítica y cultural. El objetivo de esta labor es entender la lógica interna de los stencils en relación con la ciudad, en tanto espacio físico y simbólico en el que están interviniendo. Para ello el fenómeno es abordado desde tres dimensiones diferentes: una primera dimensión que se enmarca en el análisis del discurso, el cual nos sirve para abordar a la ciudad y a los stencils como problema discursivo; una segunda dimensión que retomará herramental semiológico para distinguir los stencils y, a su vez, constituir la trama conceptual que permitirá atrapar esos discursos describiéndolos y analizándolos; y una tercera dimensión que intentará, desde la crítica cultural, analizar la función de los stencils dentro de una sociedad articulada en torno del fetichismo. Por otra parte, en este trabajo, subyace la intención de pensar críticamente la relación entre arte y política. La gran cantidad de stencils que se encuentran en todos los soportes que presta la ciudad, voluntariamente o no, en su mayoría conjugan una interrelación entre lo artístico y lo político, apareciendo como 'acciones estéticas de praxis política' que intervienen en el espacio público