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Objective: As high-field cardiac MRI (CMR) becomes more widespread the propensity of ECG to interference from electromagnetic fields (EMF) and to magneto-hydrodynamic (MHD) effects increases and with it the motivation for a CMR triggering alternative. This study explores the suitability of acoustic cardiac triggering (ACT) for left ventricular (LV) function assessment in healthy subjects (n=14). Methods: Quantitative analysis of 2D CINE steady-state free precession (SSFP) images was conducted to compare ACT’s performance with vector ECG (VCG). Endocardial border sharpness (EBS) was examined paralleled by quantitative LV function assessment. Results: Unlike VCG, ACT provided signal traces free of interference from EMF or MHD effects. In the case of correct Rwave recognition, VCG-triggered 2D CINE SSFP was immune to cardiac motion effects—even at 3.0 T. However, VCG-triggered 2D SSFP CINE imaging was prone to cardiac motion and EBS degradation if R-wave misregistration occurred. ACT-triggered acquisitions yielded LV parameters (end-diastolic volume (EDV), endsystolic volume (ESV), stroke volume (SV), ejection fraction (EF) and left ventricular mass (LVM)) comparable with those derived fromVCG-triggered acquisitions (1.5 T: ESVVCG=(56± 17) ml, EDVVCG=(151±32)ml, LVMVCG=(97±27) g, SVVCG=(94± 19)ml, EFVCG=(63±5)% cf. ESVACT= (56±18) ml, EDVACT=(147±36) ml, LVMACT=(102±29) g, SVACT=(91± 22) ml, EFACT=(62±6)%; 3.0 T: ESVVCG=(55±21) ml, EDVVCG=(151±32) ml, LVMVCG=(101±27) g, SVVCG=(96±15) ml, EFVCG=(65±7)% cf. ESVACT=(54±20) ml, EDVACT=(146±35) ml, LVMACT= (101±30) g, SVACT=(92±17) ml, EFACT=(64±6)%). Conclusions: ACT’s intrinsic insensitivity to interference from electromagnetic fields renders
Comparison of single point and equipotential bonding for I&C systems of large-area industrial sites
(1994)
Comparison of solar hot water systems in solar settlements - decentralized or centralized systems?
(2004)
Control of Aharonov-Bohm oscillations in a AlGaAs/GaAs ring by asymmetric and symmetric gate biasing
(2001)
The increasing share of renewable electricity in the grid drives the need for sufficient storage capacity. Especially for seasonal storage, power-to-gas can be a promising approach. Biologically produced methane from hydrogen produced from surplus electricity can be used to substitute natural gas in the existing infrastructure. Current reactor types are not or are poorly optimized for flexible methanation. Therefore, this work proposes a new reactor type with a plug flow reactor (PFR) design. Simulations in COMSOL Multiphysics ® showed promising properties for operation in laminar flow. An experiment was conducted to support the simulation results and to determine the gas fraction of the novel reactor, which was measured to be 29%. Based on these simulations and experimental results, the reactor was constructed as a 14 m long, 50 mm diameter tube with a meandering orientation. Data processing was established, and a step experiment was performed. In addition, a kLa of 1 h−1 was determined. The results revealed that the experimental outcomes of the type of flow and gas fractions are in line with the theoretical simulation. The new design shows promising properties for flexible methanation and will be tested.
In this paper, a coupled multiphase model considering both non-linearities of water retention curves and solid state modeling is proposed. The solid displacements and the pressures of both water and air phases are unknowns of the proposed model. The finite element method is used to solve the governing differential equations. The proposed method is demonstrated through simulation of seepage test and partially consolidation problem. Then, implementation of the model is done by using hypoplasticity for the solid phase and analyzing the fully saturated triaxial experiments. In integration of the constitutive law error controlling is improved and comparisons done accordingly. In this work, the advantages and limitations of the numerical model are discussed.
Die künftige deutsche Blitzschutznormung (2/3) – Reihe DIN EN 62305:2006 – Teil 2: Risikomanagement
(2006)
Die neue Welt
(1999)
We study the possibility to fabricate an arbitrary phase mask in a one-step laser-writing process inside the volume of an optical glass substrate. We derive the phase mask from a Gerchberg–Saxton-type algorithm as an array and create each individual phase shift using a refractive index modification of variable axial length. We realize the variable axial length by superimposing refractive index modifications induced by an ultra-short pulsed laser at different focusing depth. Each single modification is created by applying 1000 pulses with 15 μJ pulse energy at 100 kHz to a fixed spot of 25 μm diameter and the focus is then shifted axially in steps of 10 μm. With several proof-of-principle examples, we show the feasibility of our method. In particular, we identify the induced refractive index change to about a value of Δn=1.5⋅10−3. We also determine our current limitations by calculating the overlap in the form of a scalar product and we discuss possible future improvements.
Contemporary research appreciates a diverse workforce as a potential source of innovation. Researchers explore the fine details of why diversity management is central for generating innovations in heterogeneous research groups and how it could be effectively implemented into organizations. Complex research associations that discuss topics with a high impact on society increasingly address the necessity of establishing a diverse workforce to confront the challenges of tomorrow. Characterized by complex management structures as well as hierarchies, research associations have not been a subject of investigation until now. For this reason, the presented research project aims to develop a diversity and innovation management strategy with the ultimate goal of inducing change in the corporate culture. The proposed approach consisted of six phases; the first two phases investigated the status quo of diversity in the existing organizational structures of member institutes and the variety of particular working cultures within the research association. The third and the fourth phases utilized qualitative and quantitative studies. The third phase focused on the connection of management level to diversity and innovation, and the need for diversity and innovation management, and tailor-made methods of implementing them. The first three phases have been accomplished successfully; preliminary results are already available. The fourth phase will mainly focus on exploring the mind-set of the employees. The fifth phase will consolidate the findings in the first four phases into an implementable strategy. The final phase will address the implementation of this strategy into the organization. Phases 4 to 6 have not yet been undertaken
Druckindustrielle Innovation
(1998)
E0 transitions in 106Pd studied by neutron capture / G. G. Colvin ; F. Hoyler ; S. J. Robinson
(1987)
In many cities, diesel buses are being replaced by electric buses with the aim of reducing local emissions and thus improving air quality. The protection of the environment and the health of the population is the highest priority of our society. For the transport companies that operate these buses, not only ecological issues but also economic issues are of great importance. Due to the high purchase costs of electric buses compared to conventional buses, operators are forced to use electric vehicles in a targeted manner in order to ensure amortization over the service life of the vehicles. A compromise between ecology and economy must be found in order to both protect the environment and ensure economical operation of the buses.
In this study, we present a new methodology for optimizing the vehicles’ charging time as a function of the parameters CO₂eq emissions and electricity costs. Based on recorded driving profiles in daily bus operation, the energy demands of conventional and electric buses are calculated for the passenger transportation in the city of Aachen in 2017. Different charging scenarios are defined to analyze the influence of the temporal variability of CO₂eq intensity and electricity price on the environmental impact and economy of the bus. For every individual day of a year, charging periods with the lowest and highest costs and emissions are identified and recommendations for daily bus operation are made. To enable both the ecological and economical operation of the bus, the parameters of electricity price and CO₂ are weighted differently, and several charging periods are proposed, taking into account the priorities previously set. A sensitivity analysis is carried out to evaluate the influence of selected parameters and to derive recommendations for improving the ecological and economic balance of the battery-powered electric vehicle.
In all scenarios, the optimization of the charging period results in energy cost savings of a maximum of 13.6% compared to charging at a fixed electricity price. The savings potential of CO₂eq emissions is similar, at 14.9%. From an economic point of view, charging between 2 a.m. and 4 a.m. results in the lowest energy costs on average. The CO₂eq intensity is also low in this period, but midday charging leads to the largest savings in CO₂eq emissions. From a life cycle perspective, the electric bus is not economically competitive with the conventional bus. However, from an ecological point of view, the electric bus saves on average 37.5% CO₂eq emissions over its service life compared to the diesel bus. The reduction potential is maximized if the electric vehicle exclusively consumes electricity from solar and wind power.
Einfluß von Temperaturschwankungen auf das Verformungsverhalten von Rohren bei hohen Temperaturen
(1992)
The 2012 Emilia-Romagna earthquake, that mainly struck the homonymous Italian region provoking 28 casualties and damage to thousands of structures and infrastructures, is an exceptional source of information to question, investigate, and challenge the validity of seismic fragility functions and loss curves from an empirical standpoint. Among the most recent seismic events taking place in Europe, that of Emilia-Romagna is quite likely one of the best documented, not only in terms of experienced damages, but also for what concerns occurred losses and necessary reconstruction costs. In fact, in order to manage the compensations in a fair way both to citizens and business owners, soon after the seismic sequence, the regional administrative authority started (1) collecting damage and consequence-related data, (2) evaluating information sources and (3) taking care of the cross-checking of various reports. A specific database—so-called Sistema Informativo Gestione Europa (SFINGE)—was devoted to damaged business activities. As a result, 7 years after the seismic events, scientists can rely on a one-of-a-kind, vast and consistent database, containing information about (among other things): (1) buildings’ location and dimensions, (2) occurred structural damages, (3) experienced direct economic losses and (4) related reconstruction costs. The present work is focused on a specific data subset of SFINGE, whose elements are Long-Span-Beam buildings (mostly precast) deployed for business activities in industry, trade or agriculture. With the available set of data, empirical fragility functions, cost and loss ratio curves are elaborated, that may be included within existing Performance Based Earthquake Engineering assessment toolkits.
Moderne Bauwerke müssen heute eine hohe energetische Leistungsfähigkeit aufweisen und gleichzeitig alle einwirkenden Lasten sicher abtragen. Dies stellt insbesondere in Erdbebengebieten hohe Anforderungen an die verwendeten Baustoffe. Am baupraktischen Beispiel einer Doppelhaushälfte wird demonstriert, dass die Symbiose aus energieeffizientem und gleichzeitig erdbebensicherem Bauen in der höchsten deutschen Erdbebenzone mit monolithischem Ziegelmauerwerk gut realisierbar ist. Als Ziegelmauerwerk werden für die Außenwände wärmetechnisch optimierte Hochlochziegel verwendet, die sowohl die Anforderungen der Energieeinsparverordnung 2009 als auch die Anforderungen an Mauerwerkbaustoffe nach den aktuellen Erdbebennormen erfüllen. Der Erdbebennachweis der Doppelhaushälfte erfolgt mit einem nichtlinearen Nachweisverfahren, das für eine einfache praktische Anwendung programmtechnisch umgesetzt wurde. Für den Nachweis wurden aus zyklischen Schubwandversuchen ermittelte Last-Verformungskurven verwendet. Das gesamte in Deutschland noch nicht normativ geregelte Nachweiskonzept wurde im Rahmen einer Zustimmung im Einzelfall geprüft und genehmigt.
Entwicklung von Kollektoren und Speicher für solare Prozesswärmesysteme / B. Hafner ; K. Schwarzer
(1996)
Die Erdbeben in Albstadt 1978 (Magnitude 5,7), Roermond 1992 (Magnitude 5,9) oder in Waldkirch 2004 (Magnitude 5,1) haben verdeutlicht, dass die erdbebensichere Auslegung von Mauerwerksbauten auch in Deutschland von großer Bedeutung ist. Bereits im Jahr 1981 wurde die DIN 4149 (1981) “Bauten in deutschen Erdbebengebieten – Lastannahmen, Bemessung und Ausführung üblicher Hochbauten“ eingeführt, in der aber für Mauerwerksbauten nur wenige Anforderungen gestellt wurden. Diese Norm wurde durch den NABau-Arbeitsausschuss “Erdbeben; Sonderfragen“ des Deutschen Instituts für Normung e.V. (DIN) auf Grundlage des Eurocode 8 (2004) vollständig überarbeitet und durch die DIN 4149 (2005) abgelöst, die umfangreiche Regelungen für die seismische Auslegung von Mauerwerksbauten enthält. Mittlerweile liegen die DIN EN 1998-1 (2010) und der Nationale Anhang DIN EN 1998-1/NA (2011) vor, die nach Einarbeitung der Ergebnisse der durchgeführten Anwendungserprobung bauaufsichtlich eingeführt und die DIN 4149 (2005) ersetzen werden. Der folgende Beitrag gibt einen Überblick über die seismische Berechnung und Bemessung von Mauerwerksbauten nach dem europäischen Regelwerk und illustriert deren Anwendung an einem baupraktischen Beispiel.