Characterisation and Comparison of Material Parameters of 3D-Printable Absorbing Materials.

We compared different commercially available materials that are 3D-printable for their suitability for making microwave absorbers by means of additive manufacturing, i.e., 3D printing. For this, we determined their complex permittivity, and, if applicable, the complex permeability. They are responsible for the RF losses within the material and, therefore, determine its usefulness as an absorber material. Further, we made SEM (scanning electron microscope) images of material samples showing the filling materials that have been used to achieve absorbing properties

Kostenmodell der Kontextkommunikation und Kontextverarbeitung in Ubiquitären Informationsumgebungen

Die Grundidee ubiquitärer Informationssysteme ist es, dass Kleinstcomputer mehr und mehr in die Arbeits- und Lebensumgebung sowie alltägliche Gegenstände dieser Umgebungen eingebettet werden und dort demBenutzer Dienste anbieten, die ihn bei der Erledigung seiner täglichen Aufgaben unterstützen. Dabei ist eines der primären Ziele diese Dienste und die Geräte, welche die Dienste erbringen so unaufdringlich wie möglich zu gestalten. Kontext bildet dabei die Basis der Interaktion zwischen Benutzer und ubiquitärer Informationsumgebung. Kontext bezeichnet im Forschungsbereich Ubiquitous Computing Informationen über die Situation und die Umstände, die Grundlage für die Erbringung eines Dienstes sind. Kontextsensitive Anwendungen sind in der Lage auf diese Kontexte zu reagieren und und ihr Verhalten entsprechend anzupassen. Aus dem in [24] eingeführten, systemnahen Kontextmodell sowie bekannten Modellen der Kommunikation in Netzwerken und bereits in der Literatur beschriebenen Kontextmodellen, wird in diesem Artikel ein Kostenmodell für die Kommunikation und Kontextverarbeitung in ubiquitären Informationsumgebungen abgeleitet. Dieses Kostenmodell hat zum Ziel, die verschiedenen möglichen Modellierungsansätze hinsichtlich ihrer Kosten vergleichbar zu machen und so Hinweise für die effiziente Modellierung der Kommunikation und Verarbeitung von Kontexten zu geben

Improving Context Recognition In Ubiquitous Computing Environments

Ziel dieser Arbeit ist es, kontextverarbeitende Anwendungen einer ubiquitären Informationsumgebung, systematisch umzustrukturieren und zu erweitern, so dass eine signifikante Verbesserung in der Erkennung von Kontexten erreicht werden kann. Dazu wurde das Konzept des systematischen Kontextmanagements eingeführt, das eine neue Schicht innerhalb kontextverarbeitender Systeme bildet. Voraussetzung für effiziente Qualitätssicherungsmechanismen ist eine systematische und formale Ausgestaltung der Repräsentation, Verarbeitung und Kommunikation von Kontexten. Ein solches formales Modell einer ubiquitären Informationsumgebung wurde hier eingeführt. Es bildet die Grundlage des Qualitätsmanagements für Kontexte. Der zentrale Beitrag dieser Arbeit ist ein Qualitätsmanagementsystem für Kontexte auf der Basis von Kontextattributen. Attribute sind dabei allgemeine Eigenschaften von Kontextdaten, welche von der semantischen Bedeutung, die Kontexte für die Anwendungen einer ubiquitären Informationsumgebung haben, unabhängig sind. Das vorgestellte Modell definiert vier solche Attribute: das Kontextalter, die räumliche Herkunft des Kontextes, die Verlässlichkeit der Kontextinformation und die informationelle Abhängigkeit von Kontexten. Für jedes dieser Attribute werden konkrete Algorithmen und Verfahren eingeführt, welche die quantitative Beurteilung der Qualität einer Kontextinformation erlauben. Diese werden innerhalb der neu eingeführten Kontextmanagementschicht in einem Qualitätsfilter umgesetzt. Durch die Filterkomponente erhalten alle Artefakte die Möglichkeit, dynamisch die eingehenden Kontexte auf der Basis ihrer Qualitätsmaße zu filtern und so ihre eigene Dienstqualität zu verbessern. Im Ergebnis konnte, durch das hier vorgestellte Kontextmanagementsystem, eine Verbesserung der Erkennungsrate von Artefakten einer ubiquitären Informationsumgebung um bis zu 48% nachgewiesen werden.The goal of this work was to gain a significant improvement of context recognition rates of applications in ubiquitous computing environments by systematically restructuring and enhancing them. To reach this goal the concept of "Systematic Context Management" was introduced that forms a new processing layer in context sensitive systems. Systematic and formal definitions of context representation, context processing and context communication are required to build efficient quality management mechanisms. Such a formal model of a ubiquitous computing environment is introduced in this thesis. It represents the basis of a quality management system for context data. The central contribution of this work is a quality management system for contexts on basis of Context Attributes. Context Attributes are general attributes of context data that are independent from the semantically meaning of the context for an application in a ubiquitous computing environment. The presented model defines four Context Attributes: context age, spatial origin of contexts, context reliability and informational interdependence of contexts. For each of these attributes concrete algorithms and methods have been developed that allow for the quantitative assessment of context quality. These algorithms and methods are implemented in a quality-filter that is part of the newly introduced context management layer. With this filter component artefacts gain the ability to dynamically filter contexts on basis of their quality allowing for an improvement of the service quality of those artefacts. As a result of this work, it was possible to prove that by the introduction of the context management system developed in this thesis, the context recognition rate of artefacts in a ubiquitous computing environment can be improved by up to 48%

Dimensional Tolerances for Additive Manufacturing: Experimental Investigation for Fused Deposition Modeling

AbstractAdditive manufacturing creates parts in layers without using formative tools. Compared to established manufacturing processes, additive manufacturing offers many advantages. However, only a few research institutions and technology-leading companies use additive manufacturing for end-use part production because relevant challenges have not been sufficiently researched yet. Missing restrictions become apparent in the available geometrical accuracy. The objective of this investigation was the experimental determination of dimensional tolerances using standard parameters. To this end, a methodical procedure was set up. Based on experimentally determined deviations, dimensional tolerances were derived

Techno-Economic Analysis of Intermediate Pyrolysis with Solar Drying: A Chilean Case Study

Intermediate pyrolysis can be used to obtain high-quality biofuels from low-value residues such as sewage sludge or digestate. A major obstacle is the high water content of sludgy biomass, which requires an energy-intensive and expensive drying step before pyrolysis. Solar greenhouse drying is an efficient and sustainable alternative to a thermally heated belt dryer. In this study, a techno-economic assessment of intermediate pyrolysis with solar drying is carried out. Marketable products of the process are bio-oil, a substitute for diesel or heating oil, and bio-char with various possible applications. Chile is chosen as the setting of the study as its 4000 km long extension from north to south gives the opportunity to evaluate different locations and levels of solar irradiation. It is found that solar drying results in higher capital investment, but lower fuel costs. Depending on the location and solar irradiation, solar drying can reduce costs by 5–34% compared to belt drying. The break-even price of bio-char is estimated at 300–380 EUR/ton after accounting for the revenue from the liquid bio-oil

Smart-Its - communication and sensing technology for UbiComp environments

More and more Ubiquitous computing scenarios arise where computers are embedded into everyday objects as secondary ariefacts. The need for a generic platform to enhance such artifacts is addressed by the Smart-Its project. TecOs Smart- Its are small-scale embedded computer devices that can be easily attached to everyday objects and simply programmed for a special task. Just like paper Post-Its are able to add some information to an object a Smart-Its could add some computing, perception and communication capability to an object. All this capability was integrated into the tiny Smart-Its board itself that is able to operate without any additional infrastructure. This paper introduces the architecture of the Smart-Its hardware, the design decisions for the hardware itself and presents experiences we made while constructing and operating these devices; some of these experience are also based on the deployment and use of the first 160 Smart-Its devices

Novel single-source precursors for the fabrication of PbTiO3, PbZrO3 and Pb(Zr1-x Tix)O3 thin-films by chemical vapor deposition

Lead titanate, lead zirconate, and lead zirconate titanate (PZT) films in the sub-μm-range were produced at temperatures around 400 °C using novel single-source precursors in a classical thermal CVD process. The design of two bimetallic alkoxide compounds, a lead titanate and a lead zirconate source with almost identical physical properties and complement miscibility, resulted in a new quasi-single-source PZT precursor, an azeotropic mixture that evaporates at 30 °C and at a pressure of 4 × 10−1 mbar. After thermal treatment at 650 °C, transparent (100)-oriented PZT films with remnant polarization of 20 μC cm−2 and a coercive field strength of 20 V μm−1 were achieved. An additional lead source is not required

ConCom - a language and protocol for communication of context

With ConCom, we address the area of communication in wireless networks. We focus on heterogeneous settings with highly mobile devices carrying limited resources. ConCom present a way to express and communicate information, especially context, in a way that is similar to a naturally spoken language. ConCom uses sentences with a subject and attributes in its structure to represent and organize the transport of context and data. ConCom works connectionless and without addressing and forms an efficient way to exchange information in ubiquitous computing environments. We implemented ConCom and show applications taking advantage of it

Sequelae of premature birth in young adults

Background and Purpose Qualitative studies about the abnormalities appreciated on routine magnetic resonance imaging (MRI) sequences in prematurely born adults are lacking. This article aimed at filling this knowledge gap by (1) qualitatively describing routine imaging findings in prematurely born adults, (2) evaluating measures for routine image interpretation and (3) investigating the impact of perinatal variables related to premature birth. Methods In this study two board-certified radiologists assessed T1-weighted and FLAIR-weighted images of 100 prematurely born adults born very preterm (VP <32 weeks) and/or at very low birth weight (VLBW <1500 g) and 106 controls born at full term (FT) (mean age 26.8 ± 0.7 years). The number of white matter lesions (WML) was counted according to localization. Lateral ventricle volume (LVV) was evaluated subjectively and by measurements of Evans’ index (EI) and frontal-occipital-horn ratio (FOHR). Freesurfer-based volumetry served as reference standard. Miscellaneous incidental findings were noted as free text. Results The LVV was increased in 24.7% of VP/VLBW individuals and significantly larger than in FT controls. This was best identified by measurement of FOHR (AUC = 0.928). Ventricular enlargement was predicted by low gestational age (odds ratio: 0.71, 95% CI 0.51–0.98) and presence of neonatal intracranial hemorrhage (odds ratio: 0.26, 95% CI 0.07–0.92). The numbers of deep and periventricular WML were increased while subcortical WMLs were not. Conclusion Enlargement of the LVV and deep and periventricular WMLs are typical sequelae of premature birth that can be appreciated on routine brain MRI. To increase sensitivity of abnormal LVV detection, measurement of FOHR seems feasible in clinical practice