138 research outputs found
Static elasticity of cordierite I: Effect of heavy ion irradiation on the compressibility of hydrous cordierite
No full textThe effect of ion beam irradiations on the elastic properties of hydrous cordierite was investigated by means of Raman and X-ray diffraction experiments. Oriented single crystals were exposed to swift heavy ions (Au, Bi) of various specific energies (10.0-11.1 MeV/u and 80 MeV/u), applying fluences up to 5 × 1013 ions/cm2. The determination of unit-cell constants yields a volume strain of 3.4 × 10-3 up to the maximum fluence, which corresponds to a compression of non-irradiated cordierite at ~480 ± 10 MPa. The unit-cell contraction is anisotropic (e1 = 1.4 ± 0.1 × 10-3, e2 = 1.5 ± 0.1 × 10-3, and e3 = 7 ± 1 × 10-4) with the c-axis to shrink only half as much as the axes within the ab-plane. The lattice elasticity for irradiated cordierite (φ{symbol} = 1 × 1012 ions/cm2) was determined from single-crystal XRD measurements in the diamond anvil cell. The fitted third-order Birch-Murnaghan equation-of-state parameters of irradiated cordierite (V0 = 1548.41 ± 0.16 Å3, K0 = 117.1 ± 1.1 GPa, ∂K/∂P = -0.6 ± 0.3) reveal a 10-11 % higher compressibility compared to non-irradiated cordierite. While the higher compressibility is attributed to the previously reported irradiation-induced loss of extra-framework H2O, the anomalous elasticity as expressed by elastic softening (β a-1, β b-1, β c-1 = 397 ± 9, 395 ± 28, 308 ± 11 GPa, ∂(β-1)/∂P = -4.5 ± 2.7, -6.6 ± 8.4, -5.4 ± 3.0) appears to be related to the framework stability and to be independent of the water content in the channels and thus of the ion beam exposure
Abschätzung des Ablagerungsverhaltens und Reichweiten von Murgängen auf Wildbachkegel
No full textDokumentierteWildbachereignisse aus Österreich, der Schweiz sowie Norditalien (Südtirol) wurden in einer Datenbank gesammelt.Insgesamt besteht die Datenbank der erhobenen Ereignisse aus 106 Murgängen, 10 murgangartigen Ereignissen sowie 10 Ereignissen mit fluvialem Feststofftransport. Ergebnisse können zur Verbesserung von bestehenden Ansätzen, welche zur Klassifizierung verschiedener Prozesstypen dienen, herangezogen werden. Anhand dieser Ereignisdaten wurden bestehende Methoden zur Bestimmung der horizontalen Reichweite oder der Auslauflänge am Kegel getestet. Für Ereignisse mit bekanntem longitudinalem Verlauf des Fließpfades, werden dabei akzeptable Ergebnisse erzielt. Bestätigt wird auch der semi-empirische Zusammenhang zwischen Ablagerungsfläche und Ablagerungsvolumen. Die Daten dieser Studie zeigen einen ähnliche Trend wie die Daten von Iverson et al. (1998) und Crosta et al. (2003). Weiters werden zwei neu entwickelte, GIS-basierte Modelle zur Beschreibung des zweidimensionalen Auslaufverhaltens am Kegel, TopRunDF und TopFlowDF, vorgestellt. Beide Modelle verwenden einen einfachen Fließalgorithmus (beschrieben in Hürlimann et al. 2008), welcher die potentielle Ausbreitungsfläche der Murgangablagerung bestimmt. Bei TopRunDF wird die endgültige simulierte Ausbreitung des Murganges aufgrund einer empirisch basierten Flächen-Volumen Beziehung festgelegt. Die endgültige Simulation der Ausbreitung mit TopFlowDF wird aufgrund eines einfachen dynamischen Ansatzes, basierend auf Fließparameter und Reibungsgefälle bestimmt. Beide Modelle sind für die Verwendung hoch auflösender digitaler Geländemodelle (2.5 m x 2.5 m) adaptiert und wurden anhand Murgangsereignisse in der Schweiz und in Südtirol getestet. Die simulierten Ablagerungsbereiche mit TopRunDF als auch mit TopFlowDF zeigten eine gute Übereinstimmung mit den beobachteten Ablagerungsflächen.A data base of documented sediment-transporting events in torrent catchments of Austria, Switzerland and Northern Italy was established, including information on deposition volume, deposition area, the shape of the debris-fan, topological parameters and descriptions of geomorphologic features of debris events. Relations between topological parameters of the catchment including the deposition area and type of process were examined, providing a basis for improving existing classification schemes to distinguish between different torrential flow processes. Altogether 106 debris-flows events, 10 debris-flood events and 17 events with fluvial sediment transport processes were compiled. The data was used to test existing methods to predict the total travel distance or the runout distance on the fan showing acceptable results if the longidutinal profile of the flow path is known. Our data also confirm an empirical relationship between the deposition area and deposition volume, showing a similar trend as the data of Iverson et al. (1998) and Crosta et al. (2003). Two new GIS-based runout prediction methods, TopRunDF and TopFlowDF, were developed within this study. Both models use a simple flow routing algorithm, described in Hürlimann et al. (2008), to determine the potential runout area covered by debris-flow deposits. For a given volume and starting point of the deposition, a Monte-Carlo simulation is used to produce trajectories that include the spreading effect of a debris flow. TopRunDF delineates the runout zone by confining the simulated potential spreading area in the down slope direction with an empirically determined planimetric deposition area. TopFlowDF uses a simple dynamical approach based on flow parameters and a friction slope to predict deposition zones on the fan. The GIS-based simulation models were adapted to run with high resolution (2.5 m x 2.5 m) digital elevation models, generated for example from LiDAR data, and were tested with debris-flow events from Switzerland and South Tyrol for areas where LiDAR generated elevation models were available. The predicted deposition zones simulated with TopRunDF and TopFlowDF show a reasonable agreement with the observed deposition areas.by Christian ScheidlAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersZsfassung in dt. SpracheWien, Univ. für Bodenkultur, Diss., 200
Spatial feedforward for over-actuated flexible motion systems
No full textIn high-performance motion systems, e.g. waferstages or pick-and-place machines, there is an increasing demand for higher throughput and accuracy. The current design paradigm aims at rigid-body behaviour and leads in an evolutionary way to increasingly heavier systems that require more and more power. This paradigm is rapidly approaching the boundary of its scalability. A new paradigm is to design a
lightweight machine and to deal with the resulting flexibilities by over-actuation and over-sensing. Such systems offer freedom to explore new control strategies that exploit the over-actuation and -sensing. This paper presents a spatial feedforward method for over-actuated flexible motions systems, which aims at reducing the vibrations over the complete flexible structure during motion. The proposed method is experimentally validated and compared to the standard input shaping technique
Abschätzung des Ablagerungsverhaltens und Reichweiten von Murgängen auf Wildbachkegel
No full textDokumentierteWildbachereignisse aus Österreich, der Schweiz sowie Norditalien (Südtirol) wurden in einer Datenbank gesammelt.Insgesamt besteht die Datenbank der erhobenen Ereignisse aus 106 Murgängen, 10 murgangartigen Ereignissen sowie 10 Ereignissen mit fluvialem Feststofftransport. Ergebnisse können zur Verbesserung von bestehenden Ansätzen, welche zur Klassifizierung verschiedener Prozesstypen dienen, herangezogen werden. Anhand dieser Ereignisdaten wurden bestehende Methoden zur Bestimmung der horizontalen Reichweite oder der Auslauflänge am Kegel getestet. Für Ereignisse mit bekanntem longitudinalem Verlauf des Fließpfades, werden dabei akzeptable Ergebnisse erzielt. Bestätigt wird auch der semi-empirische Zusammenhang zwischen Ablagerungsfläche und Ablagerungsvolumen. Die Daten dieser Studie zeigen einen ähnliche Trend wie die Daten von Iverson et al. (1998) und Crosta et al. (2003). Weiters werden zwei neu entwickelte, GIS-basierte Modelle zur Beschreibung des zweidimensionalen Auslaufverhaltens am Kegel, TopRunDF und TopFlowDF, vorgestellt. Beide Modelle verwenden einen einfachen Fließalgorithmus (beschrieben in Hürlimann et al. 2008), welcher die potentielle Ausbreitungsfläche der Murgangablagerung bestimmt. Bei TopRunDF wird die endgültige simulierte Ausbreitung des Murganges aufgrund einer empirisch basierten Flächen-Volumen Beziehung festgelegt. Die endgültige Simulation der Ausbreitung mit TopFlowDF wird aufgrund eines einfachen dynamischen Ansatzes, basierend auf Fließparameter und Reibungsgefälle bestimmt. Beide Modelle sind für die Verwendung hoch auflösender digitaler Geländemodelle (2.5 m x 2.5 m) adaptiert und wurden anhand Murgangsereignisse in der Schweiz und in Südtirol getestet. Die simulierten Ablagerungsbereiche mit TopRunDF als auch mit TopFlowDF zeigten eine gute Übereinstimmung mit den beobachteten Ablagerungsflächen.A data base of documented sediment-transporting events in torrent catchments of Austria, Switzerland and Northern Italy was established, including information on deposition volume, deposition area, the shape of the debris-fan, topological parameters and descriptions of geomorphologic features of debris events. Relations between topological parameters of the catchment including the deposition area and type of process were examined, providing a basis for improving existing classification schemes to distinguish between different torrential flow processes. Altogether 106 debris-flows events, 10 debris-flood events and 17 events with fluvial sediment transport processes were compiled. The data was used to test existing methods to predict the total travel distance or the runout distance on the fan showing acceptable results if the longidutinal profile of the flow path is known. Our data also confirm an empirical relationship between the deposition area and deposition volume, showing a similar trend as the data of Iverson et al. (1998) and Crosta et al. (2003). Two new GIS-based runout prediction methods, TopRunDF and TopFlowDF, were developed within this study. Both models use a simple flow routing algorithm, described in Hürlimann et al. (2008), to determine the potential runout area covered by debris-flow deposits. For a given volume and starting point of the deposition, a Monte-Carlo simulation is used to produce trajectories that include the spreading effect of a debris flow. TopRunDF delineates the runout zone by confining the simulated potential spreading area in the down slope direction with an empirically determined planimetric deposition area. TopFlowDF uses a simple dynamical approach based on flow parameters and a friction slope to predict deposition zones on the fan. The GIS-based simulation models were adapted to run with high resolution (2.5 m x 2.5 m) digital elevation models, generated for example from LiDAR data, and were tested with debris-flow events from Switzerland and South Tyrol for areas where LiDAR generated elevation models were available. The predicted deposition zones simulated with TopRunDF and TopFlowDF show a reasonable agreement with the observed deposition areas.by Christian ScheidlAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersZsfassung in dt. SpracheWien, Univ. für Bodenkultur, Diss., 200
Free-space quantum key distribution over 144 km
No full textWe report on the experimental implementation of a BB84-type quantum key distribution protocol over a 144 km free-space link using weak coherent laser pulses. The security was assured by employing decoy state analysis, and optimization of the link transmission was achieved with bi-directional active telescope tracking. This enabled us to distribute a secure key at a rate of 11 bits/s at an attenuation of about 35 dB. Utilizing a simple transmitter setup and an optical ground station capable of tracking spacecraft in low earth orbit, this outdoor experiment demonstrates the feasibility of global key distribution via satellites
Entanglement-based quantum communication over 144km
No full textQuantum entanglement is the main resource to endow the field of quantum information processing with powers that exceed those of classical communication and computation. In view of applications such as quantum cryptography or quantum teleportation, extension of quantum-entanglement-based protocols to global distances is of considerable practical interest. Here we experimentally demonstrate entanglement-based quantum key distribution over 144km. One photon is measured locally at the Canary Island of La Palma, whereas the other is sent over an optical free-space link to Tenerife, where the Optical Ground Station of the European Space Agency acts as the receiver. This exceeds previous free-space experiments by more than an order of magnitude in distance, and is an essential step towards future satellite-based quantum communication and experimental tests on quantum physics in space
Correlations in noisy Landau-Zener transitions
No full textJournals published by the American Physical Society can be found at http://journals.aps.org/We analyze the influence of colored classical Gaussian noise on Landau-Zener transitions during a two-level crossing in a time-dependent regular external field. Transition probabilities and coherence factors become random due to the noise. We calculate their two-time correlation functions, which describe the response of this two-level system to a weak external pulse signal. The spectrum and intensity of the magnetic response are derived. Although the noise enters the equation of motion for the Bloch vector in a multiplicative way, nonperturbative analytic results are obtained by a resummation of diagrams in the limit of a short-noise correlation time. Our results also cover regimes where fluctuations are of the same order of magnitude as averages
Analysis of transport risks in the selected company
No full textTématem této diplomové práce je analýza přepravních rizik ve vybrané společnosti. Práce zkoumá problematiku přepravních rizik, která ohrožují přepravu zboží v rámci obchodních operací. Tato rizika spočívají v tom, že během přepravy zboží dojde k jeho poškození, zničení nebo ztrátě. V rámci případové studie je v práci podrobně zkoumáno zajištění přepravních rizik dvou dopravních společností, které se věnují mezinárodní přepravě zboží. Tato práce si položila za cíl navržení preventivních opatření, která by sloužila k prevenci přepravních rizik, nebo alespoň zmírnění dopadů na přepravní společnosti. Výsledkem případové studie je návrh opatření, která autor považuje za účinná v boji s přepravními riziky. Kdokoliv si tuto práci přečte, měl by získat základní přehled o fungování mezinárodní přepravě a její legislativě.The topic of this thesis is the analysis of transport risks in a selected company. The work examines the issue of transport risks that threaten the transport of goods in commercial operations. These risks are damaged, destroyed or lost during the transport of the goods. Within the case study, the work examines in detail the provision of transport risks of two transport companies engaged in the international transport of goods. This work aims to propose preventive measures that would serve to prevent transport risks, or at least mitigate the impact on transport companies. The result of the case study is a proposal of measures that the author considers effective in combating transport risks. Anyone who reads this work should get a basic overview of the functioning of international transport and its legislativ
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