Beitrag zur experimentellen und analytischen Beschreibung partikelförmiger Bremsenemissionen

Verkehrsbedingte Emissionen stehen derzeit stark in der öffentlichen Kritik, da diese zur Klimaveränderung beitragen und als gesundheitsgefährdend eingestuft werden. Verbrennungsmotorische Emissionen sind derzeit durch Grenzwerte reguliert. Durch den Einsatz effizienter Antriebsaggregate und effizienter Abgasnachbehandlungssysteme sank der Anteil dieser Emissionen am Gesamtfahrzeugausstoß in den vergangenen Jahren kontinuierlich. Für außermotorische Emissionen, zu denen auch partikelförmiger Bremsenabrieb zu zählen ist, existiert derzeit kein gesetzlicher Grenzwert bezüglich emittierter Partikelanzahl und Partikelmasse, was zu einem kontinuierlichen Anstieg des Anteils am Fahrzeuggesamtbudget führte. Da ein Teil der Verschleißpartikel den Größenklassen des Feinstaubes (= 10 [my]m) zugeordnet werden kann, ist diese Feinstaubquelle für die menschliche Gesundheit von besonderer Relevanz und steht damit im Fokus wissenschaftlicher Untersuchungen. Eine zielgerichtete Bewertung setzt effiziente Probenahmesysteme voraus, durch deren Anwendung eine ganzheitliche Analyse von Emissionscharakteristiken sowie der chemischen und physikalischen Eigenschaften unter Laborbedingungen und im realen Fahrversuch möglich wird. Die vorliegende Arbeit stellt einen Beitrag zur Beschreibung der Dynamik partikelförmiger Bremsenemissionen innerhalb eines geschlossenen Probenahmesystems dar. Im Einzelnen sind dies die Partikelinjektion und -verteilung bis hin zur Probenahme oder Abscheidung. Ein weiteres Ziel stellt die Verifizierung der Messfähigkeit der vornehmlich für die Ermittlung verbrennungsmotorischer Abgasemissionen entwickelten Messsysteme für den vorliegenden Anwendungsfall dar. Das übergeordnete Ziel besteht damit in einer ganzheitlichen Bewertung der zur Durchführung regulatorischer Messungen erforderlichen Mess- und Prüftechnik. Den Beginn stellt die Entwicklung einer Methodik zur Analyse des Partikelinjektions- und Abscheideverhaltens dar. Darauf aufbauend werden methodische Ansätze zur experimentellen Validierung vorgestellt. Untersuchungen zur Partikelverteilung und -abscheidung ermöglichen eine allumfassende Bewertung der ablaufenden Vorgänge. Im dritten Teil werden physikalische Messprinzipien zur Bestimmung der Partikelanzahlkonzentration (PAK), Partikelmasse (PM) bzw. -konzentration (PMK) und Größenverteilungsdichte (GVD) hinsichtlich ihrer Anwendbarkeit überprüft. Die Erarbeitung von Messkonzepten ermöglicht die Durchführung vergleichender Untersuchungen zur Bewertung von Einflussgrößen und Emissionsminderungspotenzialen. Den Abschluss bilden Untersuchungen zum Emissionsverhalten an variierenden Prüfumgebungen, vom Schwungmassen-Bremsenprüfstand bis hin zum realen Fahrversuch, was eine ganzheitliche Bewertung der Wechselwirkungen und Zusammenhänge ermöglicht.Traffic-related emissions are currently subject to strong public criticism, as they contribute to climate change and are classified as hazardous to health. Emissions from combustion engines are currently regulated by limit values. Due to the application of efficient powertrain units and exhaust aftertreatment systems, the amount of exhaust-related emissions has decreased continuously in recent years. There is currently no legal limit for non-exhaust emissions, such as particulate brake abrasion, which has led to a continuous increase in the share of vehicle global emissions. Since some of the emitted particles can be assigned to the size classes of particulate matter (= 10 µm), this source is of particular relevance to human health and is therefore the focus of scientific studies. Efficient sampling systems are required for a targeted evaluation of the health risk potential. Their application enables a holistic analysis of emission characteristics as well as the chemical and physical properties of the emitted particles under laboratory conditions and in real driving tests. The present work is a contribution to the description of brake particle emissions formation within a constant volume sampling system. In detail, this includes particle injection and particle distribution. A further objective is the evaluation of the applicability of the measurement systems developed primarily for the measurement of particulate exhaust emissions from combustion engines. The first part is the development of a methodology for the analysis of particle injection and deposition behaviour. Based on this, methodical approaches for experimental validation are presented. Investigations on particle distribution and particle deposition allow a holistic evaluation of the processes taking place. In the third part, physical measuring principles for the determination of particle number, particle mass and particle size distribution are examined with regard to applicability. The development of measurement concepts enables the execution of investigations for the evaluation of influencing variables and emission reduction potentials. The final part is the investigation of particle emission behaviour in varying test environments, from inertia dynamometer to real driving tests, which allows a holistic evaluation of interactions and correlations

Understanding the Platform Economy: Signals, Trust, and Social Interaction

Two-sided markets are gaining increasing importance. Examples include accommodation and car sharing, resale, shared mobility, crowd work, and many more. As these businesses rely on transactions among users, central aspects to virtually all platforms are the creation and maintenance of trust. While research has considered effects of trust-building on diverse platforms in isolation, the overall platform landscape has received much less attention. However, cross-platform comparison is important since platforms vary in their degree of social interaction, which, as we demonstrate in this paper, determines the adequacy and use of different trust mechanisms. Based on actual market data, we examine the mechanisms platforms employ and how frequent users rely on them. We contrast this view against survey data on users’ perceptions of the context-specific importance of these trust-building tools. Our findings provide robust evidence for our reasoning on the relation between platforms’ degree of social interaction and the associated expressive trust cues

Radio Pulses along the Galactic Plane

We have surveyed 68 deg^2 along the Galactic Plane for single, dispersed radio pulses. Each of 3027 independent pointings was observed for 68 s using the Arecibo telescope at 430 MHz. Spectra were collected at intervals of 0.5 ms and examined for pulses with duration 0.5 to 8 ms. Such single pulse analysis is the most sensitive method of detecting highly scattered or highly dispersed signals from pulsars with large pulse-to-pulse intensity variations. A total of 36 individual pulses from five previously known pulsars were detected, along with a single pulse not associated with a previously known source. Follow-up observations discovered a pulsar, PSR J1918+08, from which the pulse originated. This pulsar has period 2.130 s and dispersion measure 30 pc cm^-3, and has been seen to emit single pulses with strength up to 8 times the average.Comment: 14 pages, 5 figures, AASTeX, accepted by the Astrophysical Journa

Warrior dreams: playing Scotsmen in mainland Europe, 1945 – 2010

At the beginning of the twenty first century, thousands of adult Europeans are playing Scotsmen. They dress up in kilts and tartan, parade in military-style bagpipe bands, toss tree trunks at Highland Games, commemorate Scottish soldiers of the past, and re-enact their vision of Scottish history at ‘Celtic’ and medieval fairs. Their largest festivals attract more than 25 000 people each year, and their more elaborate clubs are recognised by Scottish Clan chiefs. The ‘Scots’ of Europe do not usually claim to be Scottish – neither by birth, descent, or residence. Their performances are Scottish masquerades, and openly declared so. Unlike their cousins in North America and Australasia, the European impersonators only very rarely insist that their Scottish performances express their ‘ethnic’ identity. And yet, the European masquerade is a quest for roots and ancestors, too. This study demonstrates that by playing Scotsmen, the ‘Scots’ of Europe attempt to reconnect with their Celtic, Nordic, or otherwise pre-modern heritage. They feel that their own customs, songs, games, and tribes were lost to the forces of modernisation – but that some of it survived in the Scottish periphery. They employ Scotland as a site of memory, as ersatz history. This thesis is a study of European nostalgia. It examines the many men and women who attempt to rediscover their traditions and histories. It is concerned with what Jay Winter calls the ‘memory boom’; the growing public preoccupation with history and its remembrance. It argues that Scotland – or rather, dreams of Scotland – have a special resonance in the European memory boom. This study touches upon the fields of public history, memory, and festive culture. In order to understand how the past is remembered and re-imagined in Europe today, the author left the archive and questioned the commemorators. This study relies on original fieldwork conducted in Belgium, France, Germany, Italy, the Netherlands, Switzerland, and Scotland during 2009 and 2010. The thesis’ focus is a qualitative one

In-situ analysis of volatiles obtained by catalytic cracking of polyethylene with HZSM-5, HY, and HMCM-41 /

When polymer/catalyst samples are heated in hydrogen, the extent of hydrogenation is reflected by reduced residue content and variations in Ea versus temperature curves. The addition of platinum increases volatile aromatic and olefin yields and/or residue content when polymer/catalyst samples are heated in helium. Bifunctional hydrogenation reactions dominate volatile product forming reactions, resulting in mainly paraffin products and small amounts of residue. Activation energy value differences between polymer/Ptcatalyst samples heated in hydrogen and the same samples heated in helium may be responsible for observed temperature shifts. The magnitudes of hydrogenation and/or platinum catalyzed effects appear to be related to catalyst pore size and acidity.Volatile product slates derived from LPE cracking/hydrocracking differ significantly with temperature, reaction atmosphere, and catalyst physical characteristics (i.e. pore size, acidity, metal loading). When thermal analysis-gas chromatography mass spectrometry and thermal analysis-mass spectrometry results are considered, volatile product variations can be rationalized by effects of catalyst acidity and/or pore size on mono- and bifunctional cracking mechanisms.When LPE is heated in helium with HZSM-5, paraffins are detected initially and olefins are produced at somewhat higher temperatures. Volatile paraffin formation by disproportionation reactions catalyzed by external HZSM-5 acid sites is favored due to the low activation energy values for this pathway at low temperatures. Small olefins (C3--C5) are the most abundant products when HZSM-5 and HMCM-41 catalysts are employed for cracking LPE. In contrast, cracking with HY produces primarily paraffin volatile products (C4--C8). HY pores are large enough and acid sites are strong enough to promote disproportionation reactions, which lead to formation of volatile paraffins.A variety of plastic waste recycling methods have been established and new recycling approaches are being developed to avoid placing polymers into landfills. One approach to waste plastic recycling, known as tertiary recycling, consists of decomposing plastics into useful chemicals or fuels. Repetitive injection thermal analysis gas chromatography mass spectrometry and thermal analysis mass spectrometry allow us to identify and quantify volatile products evolved from complex temperature-dependent systems. Volatile products from cracking/hydrocracking of low molecular weight polyethylene (LPE) were analyzed and activation energies of formation were determined when HZSM-5, HY, HMCM-41, and their platinum loaded analogs were employed as cracking catalysts

Henderson-Ouachita Faculty Woodwind Quintet

This is the program for the Henderson-Ouachita Faculty Woodwind Quintet concert held on March 27, 1973, in Mitchell Hall Auditorium. The Henderson faculty included David Etienne on flute, Wanda Jackson on oboe, and Earl Hesse on clarinet. The Ouachita faculty included Gregory Umber on horn and Charles Wesley on bassoon

Sublogarithmic uniform Boolean proof nets

Using a proofs-as-programs correspondence, Terui was able to compare two models of parallel computation: Boolean circuits and proof nets for multiplicative linear logic. Mogbil et. al. gave a logspace translation allowing us to compare their computational power as uniform complexity classes. This paper presents a novel translation in AC0 and focuses on a simpler restricted notion of uniform Boolean proof nets. We can then encode constant-depth circuits and compare complexity classes below logspace, which were out of reach with the previous translations.Comment: In Proceedings DICE 2011, arXiv:1201.034

IBA ALZETTE-BELVAL+ A MEMORANDUM

The report documents the involvement of the University of Luxembourg's Department of Geography & Spatial Planning in the pre-figuration of an International Building Exhibition (IBA) in the cross-border territory of Alzette-Belval (Luxembourg-France). As a memorandum, it sets out to address the main goals of this endeavour and embeds the case in the literature on related activities. Moreover, it reports on the field research activities undertaken in order to set the stage for a possible IBA. As a result of the rather contested findings and also in light of the uncertainty among the political institutions whether and how to bring this to practice, the process of pre-figuring the IBA was terminated without leading to full implementation

Comparison of methods for sampling particulate emissions from tires under different test environments

Traffic-related emissions are strongly criticised by the public because they contribute to climate change and are classified as hazardous to health. Combustion engine emissions have been regulated by limit values for almost three decades. There is currently no legal limit for non-exhaust emissions, which include tire wear particle emissions and resuspension. As a result, the percentage of total vehicle emissions has risen continuously. Some of the particles emitted can be assigned to the size classes of particulate matter (≤10 µm) and are therefore of particular relevance to human health. The literature describes a wide range of concepts for sampling and measuring tire wear particle emissions. Because of the limited number of studies, the mechanisms involved in on-road tests and their influence on the particle formation process, particle transport and the measuring ability can only be described incompletely. The aim of this study is to compare test bench and on-road tests and to assess the influence of selected parameters. The first part describes the processes of particle injection and particle distribution. Based on this, novel concepts for sampling and measurement in the laboratory and in the field are presented. The functionality and the mechanisms acting in each test environment are evaluated on the basis of selected test scenarios. For example, emissions from external sources, the condition of the road surface and the influence of the driver are identified as influencing factors. These analyzes are used to illustrate the complexity and limited reproducibility of on-road measurements, which must be taken into account for future regulations