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The use of nematic liquid crystal (LC) mixtures for microwave frequency applicationspresents a fundamental drawback: many of these mixtures have not been properly characterizedat these frequencies, and researchers do not have an a priori clear idea of which behavior they canexpect. This work is focused on developing a new procedure for the extraction of the main parametersof a nematic liquid crystal: dielectric permittivity and loss tangent at 11 GHz under differentpolarization voltages; splay elastic constantK11, which allows calculation of the threshold voltage(Vth); and rotational viscosityγ11, which allows calculating the response time of any arbitrary device.These properties will be calculated by using a resonator-based method, which is implementedwith a new topology of substrate integrated transmission line. The LC molecules should be rotated(polarized) by applying an electric field in order to extract the characteristic parameters; thus,the transmission line needs to have two conductors and low electric losses in order to preserve theintegrity of the measurements. This method was applied to a well-known liquid crystal mixture(GT3-23002 from MERCK) obtaining the permittivity and loss tangent versus bias voltage curves,the splay elastic constant, and the rotational viscosity of the mixture. The results validate the viabilityof the proposed method.
For audio signals, we use the sign of the coefficients of the redundant discrete wavelet transform to generate primary hash vectors assigning bit 1 to positive or zero coefficients and bit 0 in the negative case. Discarding the highest frequency band and using a 6 step transform we get for each sample a 6 bit primary hash value which we may save as an integer. We then select a possible primary hash value (in our experiments we chose 0 or 63) and take the time indices where this primary hash value occurs as the secondary hash vector which is attributed to the whole audio signal. Comparing two audio signals, the number of elements in the intersection of the corresponding time indices are called "number of matches", a high number may indicate a similarity between the files. This secondary hash vector turns out to be robust against addition of noise, GSM-, G.726-, MP3 coding and packet loss. It may therefore be useful to detect spam telephone calls without analyzing the semantic content by the similarity of the corresponding signals. An algorithm is given to detect similar but shifted signals. Results of experiments are reported using a test corpus of 5 000 audio files of regular calls and 200 audio files of different versions of 20 original spam recordings augmented by a set of 45 files of different versions of 9 "special spam" signals.
Das für diese Masterthesis realisiertes Softwaresystem verwendet als Teilkomponente die Softwarelösung IPEE (Internet Pattern Extrakt Engine), die von M.Sc. Andreas Frey entwickelt und in der ursprünglichen Fassung dokumentiert wurde. Diese Kapitel sind aus Gründen des Copyrights, die auf der Software IPEE liegen, nicht in der veröffentlichten Fassung (der Masterthesis) enthalten. Eingeleitet wird die Arbeit mit Aspekten des Entwicklungsstandes des Semantik Web (Web3.0). Es folgt die Begriffsdefinition der Semantik und der semantisch orientierten Verarbeitung. Für die Ablage (Archivierung) und Verarbeitung von Daten für semantisch orientierte verarbeitende Systeme eignet sich die Konzeption der semistrukturierten Daten, die darauf folgend definiert und mit den anderen Konzeptionen - wie strukturiert und nicht strukturiert - in Beziehung gesetzt wird. In den folgenden Kapiteln werden die Komponenten erklärt, die für die Realisierung eines Prototypen zur semantisch orientierten Verarbeitung verantwortlich sind und hauptsächlich auf Aspekte der semantisch orientierten Verarbeitung von Verben fokussiert sind. Von Relevanz sind hierbei Komponenten zur Wort- und Phrasen-Analyse und zur automatischen Recherche von Wörtern aus dem Internet. Da diese Komponenten auf die Realisierung von Pattern-Extraktionsverfahren basieren, wurde die spezielle Softwarelösung IPEE verwendet. Des weiteren werden Komponenten für die Generierung des semantischen Graphen und die Visualisierung anhand von hyperbolischen Bäumen mit Hilfe einer Open Source Software Treebolic Browser beschrieben. Auch wird eine GUI für die Eingabe und Verarbeitung von Sätzen der deutschen Sprache und die Verwaltung eines Bedeutungswörterbuches erklärt. Abschließend erfolgt eine experimentelle Auswertung der semantisch orientierten Verarbeitung.
The publish or perish culture of scholarly communication results in quality and relevance to be are subordinate to quantity. Scientific events such as conferences play an important role in scholarly communication and knowledge exchange. Researchers in many fields, such as computer science, often need to search for events to publish their research results, establish connections for collaborations with other researchers and stay up to date with recent works. Researchers need to have a meta-research understanding of the quality of scientific events to publish in high-quality venues. However, there are many diverse and complex criteria to be explored for the evaluation of events. Thus, finding events with quality-related criteria becomes a time-consuming task for researchers and often results in an experience-based subjective evaluation. OpenResearch.org is a crowd-sourcing platform that provides features to explore previous and upcoming events of computer science, based on a knowledge graph. In this paper, we devise an ontology representing scientific events metadata. Furthermore, we introduce an analytical study of the evolution of Computer Science events leveraging the OpenResearch.org knowledge graph. We identify common characteristics of these events, formalize them, and combine them as a group of metrics. These metrics can be used by potential authors to identify high-quality events. On top of the improved ontology, we analyzed the metadata of renowned conferences in various computer science communities, such as VLDB, ISWC, ESWC, WIMS, and SEMANTiCS, in order to inspect their potential as event metrics.
Das Ziel der vorliegenden Arbeit besteht darin, die Frage zu beantworten wie Yosys Verilog einliest und daraus RTLIL generiert. Mit der Beantwortung dieser Frage, soll die Datenstruktur RTLIL und die Verknüpfung zu einem Verilog Design besser verstanden werden. Dafür wurde das Frontend von Yosys untersucht und die Datenstruktur RTLIL näher eleuchtet. Als Ergebnis konnte festgehalten werden, dass die AstNode Datenstruktur eine wesentliche Rolle bei der Konvertierung von Verilog zu RTLIL spielt, und mit deren Hilfe beim Einlesen ein abstrakter Syntaxbaum gebildet wird. Allein der Typ des Knotens beeinflusst, wie der RTLIL Generator damit umgeht. Weiter ist die Generierung von RTLIL::Cell Objekten als erster Schritt zur Synthese zu verstehen, da sie durch Technologie Mapping reale Komponenten abbilden können
A level graph G = (V,E,λ) is a graph with a mapping λ : V → {1,...,k}, k ≥ 1, that partitions the vertex set V as V = V1 ∪...∪ Vk, Vj = λ-1(j), Vi ∩ Vj = ∅ for i ≠ j, such that λ(v) = λ(u) + 1 for each edge (u, v) ∈ E. Thus a level planar graph can be drawn with the vertices of every Vj, 1 ≤ j ≤ k, placed on a horizontal line, representing the level lj , and without crossings of edges, which can be drawn as straight line segments between the levels. Healy, Kuusik and Leipert gave a complete characterization of minimal forbidden subgraphs for level planar graphs (MLNP patterns) for hierarchies [4]. Minimal in terms of deleting an ar- bitrary edge leads to level planarity. A radial graph partitions the vertex set on radii, which can be pictured as concentric circles, instead of levels, lj = (j cos(α), j sin(α)), α ∈ [0,2π), mapped around a shared center, where j, 1 ≤ j ≤ k indicates the concentric circles’ radius. Comparing embeddings of radial graphs with that of level graphs we gain a further possibility to place an edge and eventually avoid edge crossings which we wish to prevent for planarity reasons. This offers a new set of minimal radial non planar subgraphs (MRNP patterns). Some of the MLNP pat- terns can be adopted as MRNP patterns while some turn out to be radial planar. But based on the radial planar MLNP patterns and the use of augmentation we can build additional MRNP patterns that did not occur in the level case. Furthermore we point out a new upper bound for the number of edges of radial planar graphs. It depends on the subgraphs in- duced between two radii. Because of the MRNP patterns these subgraphs can either consist of a forest or a cycle with several branches. Applying the bound we are able to characterize extremal radial planar graphs. Keywords: radial graphs, minimal non-planarity, extremal radial planar