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See detailDer Ulmener Burgfrieden von 1399 in seinem historischen Kontext
Kreutz, Bernhard René UL

in Hirbodian, Sigrid; Jörg, Christian; Klapp, Sabine (Eds.) et al Pro multis beneficiis. Festschrift für Friedhelm Burgard. Forschungen zur Geschichte der Juden und des Trierer Landes (2012)

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See detailUltimate strengths of FRC rectangular columns subjected to simulated seismic loading: Experimental database and new models
Cai, Gaochuang UL; Degee, Herve

in Archives of Civil and Mechanical Engineering (2017)

While there are many experimental investigations focusing on seismic behaviour of fibre reinforced concrete (FRC) columns, the studies regarding the accuracies and conservativeness of existing seismic ... [more ▼]

While there are many experimental investigations focusing on seismic behaviour of fibre reinforced concrete (FRC) columns, the studies regarding the accuracies and conservativeness of existing seismic strength models of FRC columns are limited. This paper presents a seismic research database of 322 FRC columns obtained from a comprehensive literature investigation. The characteristic of the database and the effects of main variables on the seismic strengths of FRC columns are analyzed in detail, the accuracies of existing strength models of FRC column are also examined as well. In addition, using the database, considering the effects of fibre and other structural factors on FRC columns, Priestley et al. shear and CFB-FIP moment models are modified respectively. Results show that the two proposed strength models both present better evaluation than other models. On the other hand, a detailed method for assessing the potential failure mode of FRC column subjected to seismic loads is also suggested using the two strength models. The comparative results verify the feasibilities and accuracies of the assessment method in FRC columns. [less ▲]

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See detailUltra-Broadband Bow-tie Antenna
Moonshiram, Anusha UL; Marso, Michel UL

in NNGT International Journal on Networking and Communication (2015), 4

An ultra-broadband bow-tie with a VSWR < 2 from 5 to 60 GHz is revealed. The bow-tie antenna shows frequency independence properties and resonates periodically at multiples of its resonance frequency of 7 ... [more ▼]

An ultra-broadband bow-tie with a VSWR < 2 from 5 to 60 GHz is revealed. The bow-tie antenna shows frequency independence properties and resonates periodically at multiples of its resonance frequency of 7.7 GHz with the return loss always less than -10 dB. The antenna is linearly polarized and has a maximum directivity of 6 dBi in both the elevation and azimuth planes in the farfield. The antenna is a symmetrical design with straight ends and a flare angle of 90°. It is a simple metal layer on top of a substrate layer which is fed on the metal layer right at the center with closely spaced coplanar striplines. The flare angle and the straight-end of the bow-tie antenna are varied and the 90° straight-end bow-tie antenna is compared with three other bow-tie antennas with flare angle of 60° and round-ends. All four bow-tie antennas have a low VSWR. The E-fields, H-fields and impedance plots of the ultra-broadband bow-tie antenna are shown. The impedance plot is in fact the impedance of frequency independent antennas of 189Ω or 60π across all frequencies. [less ▲]

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See detailUltra-high Precision, Absolute, Earth Gravity Measurements PhD Thesis
Rothleitner, Christian UL

Doctoral thesis (2008)

Within the framework of this thesis two apparatuses for an absolute measurement of gravity were designed, constructed, and tested for the purpose of detecting long-term variations of gravity, determining ... [more ▼]

Within the framework of this thesis two apparatuses for an absolute measurement of gravity were designed, constructed, and tested for the purpose of detecting long-term variations of gravity, determining the absolute gravity value for metrological applications, and for research in fundamental physics. The work includes a stationary gravimeter, which functions as a highly accurate reference system and a portable gravimeter, which is aimed for field measurements. The principle these gravimeters use to determine the gravity value is based on the relation between the falling distance, the falling time, and the acceleration due to gravity. A Michelson interferometer measures the distance change between a falling object mirror and an inertial reference mirror with a Helium-Neon laser (633 nm). The whole fringe signal is digitized by a high-speed ADC, which is disciplined by a rubidium frequency standard. This fringe recording is novel compared to common gravimeters, which use an analogue zero-crossing determination. [less ▲]

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See detailUltra-long ordered nanowires from the concerted self-assembly of discotic liquid crystal and solvent molecules.
Park, J. H.; Kim, K. H.; Park, Y. W. et al

in Langmuir (2015), 31(34), 9432-9440

The realization of long and aligned molecular wires is a great challenge and different approaches have been proposed. Interestingly, hexapentyloxytriphenylene (HAT5) discotic liquid crystal molecules ... [more ▼]

The realization of long and aligned molecular wires is a great challenge and different approaches have been proposed. Interestingly, hexapentyloxytriphenylene (HAT5) discotic liquid crystal molecules, model system of molecules with flat and aromatic cores, can spontaneously form well aligned, micrometer long yet only tens of nanometers thick nanowires on solid surfaces. We have investigated the formation mechanism of these wires by using different solvents with selected characteristics like chemical structure, boiling point, vapor pressure and surface tension. When casting from toluene and benzene solutions, atomic force microscopy reveals that the discotics spontaneously form very long and thin wires, self-aligning along a common orientation. If instead dodecane or heptane are used, different and in general thicker structures are obtained. The chemical structure of the solvent appears to have a key role, coupling to the liquid crystal self-assembly by allowing solvent molecules to enter in the ordered structure if their design matches the core of HAT5 molecules, thereby guiding the assembly. However, also other aspects are relevant in the assembly, like the nature of the substrate or the rate of solvent evaporation, and these can favor or interfere with the self-assembly into long structures. The use of solvents with aromatic structure is advantageous not only because it affects the geometry of the assembly, promoting long wire formation, but it is also compatible with good quality of the intermolecular order, as suggested by a high anisotropy of the Raman spectra of the nanowires formed from these solvents. Finally, the electrical properties of ordered systems show a clearly higher electrical conductivity compared to the disorganized aggregates. [less ▲]

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See detailUltrafast and highly sensitive photodetectors fabricated on high-energy nitrogen-implanted GaAs,
Mikulics, M.; Marso, Michel UL; Kordoš, P. et al

in Applied Physics Letters (2003), 83

We have fabricated and tested metal–semiconductor–metal ~MSM! photodetectors based on nitrogen-ion-implanted GaAs. Nitrogen ions with energy of 700 and 880 keV, respectively, were implanted into epitaxial ... [more ▼]

We have fabricated and tested metal–semiconductor–metal ~MSM! photodetectors based on nitrogen-ion-implanted GaAs. Nitrogen ions with energy of 700 and 880 keV, respectively, were implanted into epitaxial GaAs films at an ion concentration of 331012 cm22. Ti/Au MSM photodetectors with 1-um-wide fingers were fabricated on top of the implanted GaAs. In comparison to low-temperature-grown GaAs photodetectors, produced in parallel in identical MSM geometry, the 880 keV N1-implanted photodetectors exhibited almost two orders of magnitude lower dark current ~10 nA at 1 V bias! and the responsivity more than doubled ~.20 mA/W at 20 V bias!. Illumination with 100-fs-wide, 810 nm wavelength laser pulses, generated ;2.5-ps-wide photoresponse signals with amplitudes as high as 2 V. The 2.5 ps relaxation time was the same for both the ion-implanted and low-temperature-grown devices and was limited by the MSM capacitance time constant. [less ▲]

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See detailUltrafast and Highly-Sensitive Photodetectors with Recessed Electrodes Fabricated on Low-Temperature-Grown GaAs
Mikulics, M.; Wu, S.; Marso, Michel UL et al

in IEEE Photonics Technology Letters (2006), 18 (2006)(5-6), 820-822

We have fabricated and characterized ultrafast metal–semiconductor–metal (MSM) photodetectors with recessed electrodes, based on low-temperature-grown GaAs. The new recessed-electrode MSM geometry led to ... [more ▼]

We have fabricated and characterized ultrafast metal–semiconductor–metal (MSM) photodetectors with recessed electrodes, based on low-temperature-grown GaAs. The new recessed-electrode MSM geometry led to an improved electric-field distribution inside the photodetector structure and resulted in a 25% breakdown voltage and sensitivity increase with simultaneous four-fold reduction of capacitance, as compared to the identical MSM devices with planar electrodes. Time-resolved studies performed using 100-fs-duration laser pulses showed that recessed-electrode MSMs exhibited 1.0-ps-wide photoresponse transients with no slow after-pulse tails and their photoresponse time was 0.9 ps. The improved transient photoresponse parameters are the main advantages of the recessed-electrode geometry. [less ▲]

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See detailUltrafast electron-phonon decoupling in graphite
Ishioka, Kunie; Hase, Muneaki; Kitajima, Masahiro et al

in Physical Review B (2008), 77(12),

We report the ultrafast dynamics of the 47.4 THz coherent phonons of graphite interacting with a photoinduced nonequilibrium electron-hole plasma. Unlike conventional materials, upon photoexcitation the ... [more ▼]

We report the ultrafast dynamics of the 47.4 THz coherent phonons of graphite interacting with a photoinduced nonequilibrium electron-hole plasma. Unlike conventional materials, upon photoexcitation the phonon frequency of graphite upshifts, and within a few picoseconds relaxes to the stationary value. Our first-principles density functional calculations demonstrate that the phonon stiffening stems from the light-induced decoupling of the nonadiabatic electron-phonon interaction by creating a nonequilibrium electron-hole plasma. Time-resolved vibrational spectroscopy provides a window on the ultrafast nonquilibrium electron dynamics. [less ▲]

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See detailUltrafast Low-Temperature-Grown Epitaxial GaAs Photodetectors Transferred on Flexible Plastic Substrates
Mikulics, M.; Adam, R.; Marso, Michel UL et al

in IEEE Photonics Technology Letters (2005), 17(8), 1725-1727

We demonstrate low-temperature (LT)-grown GaAs photodetectors transferred on flexible polyethylene terephthalate (PET) plastic substrates. The LT-GaAs layer was patterned into 20 20 m2 chips, which after ... [more ▼]

We demonstrate low-temperature (LT)-grown GaAs photodetectors transferred on flexible polyethylene terephthalate (PET) plastic substrates. The LT-GaAs layer was patterned into 20 20 m2 chips, which after placing on the PET substrates were integrated with coplanar strip transmission lines. The devices exhibit low dark currents ( 2 10 8 A), subpicosecond photoresponse time, and signal amplitudes up to 0.9 V at the bias voltage of 80 V and under laser beam excitation power of 8 mW at 810-nm wavelength. At the highest bias ( 80 V) level, an increase of the response time (up to 1.3 ps) was observed and attributed to the influence of heating effects due to low thermal conductivity of PET. Our LT-GaAs-on-PET photodetectors withstand hundredfold mechanical bending of the substrate and are intended for applications in hybrid optoelectronic circuits fabricated on noncrystalline substrates, in terahertz imaging, and in biology-related current-excitation tests. [less ▲]

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See detailUltrafast metal-semiconductor-metal photodetectors on low-temperature-grown GaN
Mikulics, M.; Marso, Michel UL; Javorka, P. et al

in Applied Physics Letters (2005), 86(21), 211110

We have fabricated and characterized ultrafast metal-semiconductor-metal photodetectors based on low-temperature-grown sLTd GaN. The photodetector devices exhibit up to 200 kV/cm electric breakdown fields ... [more ▼]

We have fabricated and characterized ultrafast metal-semiconductor-metal photodetectors based on low-temperature-grown sLTd GaN. The photodetector devices exhibit up to 200 kV/cm electric breakdown fields and subpicosecond carrier lifetime. We recorded as short as 1.4-ps-wide electrical transients using 360-nm-wavelength and 100-fs-duration laser pulses, that is corresponding to the carrier lifetime of 720 fs in our LT GaN material. [less ▲]

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See detailUltrafast Phenomena in Freestanding LT-GaAs Devices
Marso, Michel UL; Mikulics, M.; Adam, R. et al

in Acta Physica Polonica A (2005), VOL 107; PART 1

We report on the fabrication and high-frequency performance of our photodetectors and photomixers based on freestanding low-temperature-grown GaAs. The MBE-grown low-temperature GaAs layers are lifted ... [more ▼]

We report on the fabrication and high-frequency performance of our photodetectors and photomixers based on freestanding low-temperature-grown GaAs. The MBE-grown low-temperature GaAs layers are lifted from the native GaAs substrate and transferred on top of variety of host substrates. The freestanding devices exhibit breakdown electrical ¯elds above 200 kV/cm and dark currents below 3 £ 10¡7 A at 100 V bias. Device photoresponse shows 0.55 ps wide electrical transients with voltage amplitudes up to 1.3 V, measured using an electro-optical sampling technique with 100 fs wide laser pulses. Photomixing experiments at 460 GHz yield a 9 times higher output power for the freestanding device on Si/SiO2 host substrate compared to the native substrate. [less ▲]

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See detailUltrastrukturelle Unterscheidung von sympathischen und sensiblen Nervenfasern in Ventrikelmyokard des Schweins.
Schramm, Erhard; Meßlinger, Karl; Hanesch, Ulrike UL et al

in Zeitschrift für Kardiologie (1993), 82(Suppl. 3), 34

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See detailUm die Ecke ins Exil. Saaremigranten in Luxemburg zwischen 1935 und 1940
Schreiber, Catherina UL

in Saargeschichte|n (2013), (1), 24-30

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See detail"Umberto Eco, un lettré populaire"
Roelens, Nathalie UL

Presentation (2017)

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See detailUmberto Eco: Die geheimnisvolle Flamme der Königin Loana. Ein Buchtipp.
Küpper, Achim UL

in http ://www.arte-tv.com (2005)

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See detailUmbildungsarbeiten am Mytos. Ralf Rothmanns Archäologie(n) des Ruhrgebietes
Heimböckel, Dieter UL

in Mein, Georg; Amann, Wilhelm; Parr, Rolf (Eds.) Periphere Zentren oder zentrale Peripherien? Kulturen und Regionen Europas zwischen Globalisierung und Regionalität (2008)

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See detailUmdeutung der Geschichte: Erzbischof Balduin, Kaiser Heinrich VII. und der Italienzug in der Trierer Bilderchronik und den Gesta Naldewini
Margue, Michel UL

in Nolden, Reiner (Ed.) Balduin von Luxemburg. Erzbischof und Kurfürst von Trier (1308-1354). Vorträge eines Kolloquiums in Trier im Juni 2008 (2008)

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See detailUmfrage - Einführung in die Methoden der Umfrageforschung
Jacob, Rüdiger; Heinz, Andreas UL; Decieux, Jean Philippe Pierre UL

Book published by Oldenbourg Wissenschaftsverlag - 3 (2013)

Das Buch vermittelt theoretische Grundlagen und praxisnahe Kenntnisse zu wissenschaftlichen Umfragen. Mit Hilfe dieser Kenntnisse soll der Leser Umfragen sowohl kritisch beurteilen als auch selbst nach ... [more ▼]

Das Buch vermittelt theoretische Grundlagen und praxisnahe Kenntnisse zu wissenschaftlichen Umfragen. Mit Hilfe dieser Kenntnisse soll der Leser Umfragen sowohl kritisch beurteilen als auch selbst nach den gültigen wissenschaftlichen Standards durchführen können. Damit soll dem in den letzten Jahren zunehmenden Problem mangelnder Gültigkeit und Zuverlässigkeit von Befragungsdaten entgegengewirkt werden. Der Schwerpunkt liegt auf Hinweisen zur Formulierung von Fragen und zur Konstruktion von Fragebögen, daneben werden aber auch viele andere Probleme behandelt, wie z.B. Fragen des Forschungsdesigns oder der Planung und Durchführung der Feldarbeit. Neben postalischen, persönlichen und telefonischen Befragungen werden in der zweiten Auflage auch Online-Befragungen behandelt. Das Buch soll damit die Lücke zwischen allgemeinen Lehrbüchern zur empirischen Sozialforschung einerseits und speziellen Lehr- und Handbüchern zur Datenanalyse andererseits schließen. [less ▲]

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