TY - RPRT A1 - Unger, J. A1 - Rück, Thomas A1 - Landgraf, Ferdinand A1 - Bierl, Rudolf T1 - Herstellung und Analyse der Resonanzfrequenz eines MEMS Cantilever für das CEPAS Verfahren N2 - Diese Abhandlung beschreibt das Konzept eines mikroeletromechanischen Systems (MEMS), das im Messverfahren der cantilever enhanced photoacoustic spectroscopy (CEPAS) Verwendung finden soll. Es wird die Herstellung eines einseitig eingespannten Biegebalkens aus Silizium mittels deep reactiv ion etching (DRIE) beschrieben. Des Weiteren wird die Resonanzfrequenz dieses Cantilevers mit Hilfe Laservibrometertechnik untersucht. Die resultierenden resonanten Schwingungen 0.Ordnung werden mit den Ergebnissen einer vereinfachten theoretischen Näherung verglichen. Die Messergebnisse stehen in gutem Zusammenhang mit den theoretischen Werten. Solche Cantilever, die aus silicon on insula tor (SOI) Wafer angefertigt wurden, weisen bei einer Zielfrequenz ein mittlere Abweichung von Δf = 118±26Hz (bzw.Δf =0,76±0,17%) auf. Y1 - 2015 ER - TY - CHAP A1 - Holler, Sven A1 - Hausler, Peter A1 - Roth, Carina A1 - Bierl, Rudolf T1 - Gestapelte Au-Al-Au und Au-Ag-Au Schichten als aktive Schichten für die Oberflächenplasmonenresonanzspektroskopie T2 - 5. Landshuter Symposium Mikrosystemtechnik, März 2016 Y1 - 2016 SN - 978-3-9812696-9-7 SP - 192 EP - 198 PB - Fachhochschule Landshut CY - Landshut ER - TY - CHAP A1 - Roth, Carina A1 - Hausler, Peter A1 - Bierl, Rudolf T1 - Einbindung eines CMOS-Detektors in einen hochintegrierten SPR-Sensor T2 - 5. Landshuter Symposium Mikrosystemtechnik, März 2016 Y1 - 2016 SN - 78-3-9812696-9-7 SP - 200 EP - 205 PB - Fachhochschule Landshut CY - Landshut ER - TY - CHAP A1 - Lang, Christian A1 - Steinborn, Florian A1 - Steffens, Oliver A1 - Lang, Elmar Wolfgang ED - Valenzuela, O. ED - Rojas, F. ED - Herrera, L.J. ED - Pomares, H. ED - Rojas, I. T1 - Applying a 1D-CNN Network to Electricity Load Forecasting T2 - Theory and Applications of Time Series Analysis N2 - This paper presents a convolutional neural network (CNN) which can be used for forecasting electricity load profiles 36 hours into the future. In contrast to well established CNN architectures, the input data is one-dimensional. A parameter scanning of network parameters is conducted in order to gain information about the influence of the kernel size, number of filters and number of nodes. Furthermore, different dropout methods are applied to the CNN and are evaluated. The results show that a good forecast quality can already be achieved with basic CNN architectures, the dropout improves the forecast. The method works not only for smooth sum loads of many hundred consumers, but also for the load of single apartment buildings. KW - Energy load forecasting KW - STLF KW - Neural networks KW - CNN KW - Convolutional networks Y1 - 2020 U6 - https://doi.org/10.1007/978-3-030-56219-9_14 SP - 205 EP - 218 PB - Springer ER - TY - JOUR A1 - Reuther, Maike A1 - Steffens, Oliver T1 - Evaluation der Bauteiltemperierung für den Herzogskasten Abensberg JF - Bauphysik N2 - Die These, dass die Methode der direkten Temperierung von erdberührten oder anderweitig feuchtebelasteten Bauteilen zur Beseitigung von Feuchteschäden in Bestandsgebäuden auch die Energieeffizienz des Gebäudes erhöhen und sogar ohne weitere energetische Sanierungsmaßnahmen die Anforderungen der Energieeinsparverordnung (EnEV) erfüllen kann, wird anhand des als Museum genutzten Herzogskastens in Abensberg überprüft. In Verbindung mit einer Evaluation der Trocknungswirkung wird die Gebäude-Energieeffizienz durch Vergleich von Bedarfsberechnungen auf Basis der DIN V 18599 mit realen Verbrauchszahlen überprüft und diskutiert. KW - Bauteiltemperierung KW - energetische Sanierung KW - Gebäudeenergieeffizienz KW - Mauerwerkstrocknung KW - Denkmal KW - Restaurierung KW - DIN V 18599 KW - EnEV Y1 - 2015 U6 - https://doi.org/10.1002/bapi.201510010 VL - 37 IS - 2 SP - 96 EP - 99 PB - Ernst & Sohn, a Wiley Brand ER - TY - RPRT A1 - Schlamp, Matthias A1 - Ehrlich, Ingo ED - Baier, Wolfgang T1 - Analyse des Impact-Verhaltens gekrümmter Strukturbauteile von Luftfahrzeugen zur Entwicklung eines Strukturüberwachungssystems für faserverstärkte Kunststoffe - BIRD T2 - Forschung 2019 / Ostbayerische Technische Hochschule Regensburg N2 - Die in Flugvorausrichtung weisenden Bauteile von Luftfahrzeugen sind oftmals durch Einschläge aufgrund von Vogelschlag, Hagel oder aufgewirbelten Kleinteilen gefährdet. Diese Einschläge, sogenannte Impacts, weisen bei faserverstärkten Kunststoffen ein stark krümmungs- und materialabhängiges Verhalten und Schadensausmaß auf. Impact-Schädigungen führen oftmals zu hohen Reparaturkosten, welche durch eine genauere Kenntnis des Schadens verringert werden können. Zur Klassifizierung dieser Schädigungen steht dabei vor allem das auftretende Frequenz signal des Impacts im Fokus der Untersuchungen. Y1 - 2019 UR - https://doi.org/10.35096/othr/pub-789 SN - 978-3-9818209-6-6 SP - 40 EP - 41 PB - VMK Verlag für Marketing & Kommunikation GmbH & Co. KG ER - TY - JOUR A1 - Romano, Marco A1 - Micklitz, Matthias A1 - Olbrich, Florian A1 - Bierl, Rudolf A1 - Ehrlich, Ingo A1 - Gebbeken, Norbert T1 - Experimental investigation of damping properties of unidirectionally and fabric reinforced plastics by the free decay method JF - Journal of Achievements in Materials and Manufacturing Engineering N2 - Purpose: of this paper is experimental investigation of damping properties of unidirectionally and fabric reinforced plastics by the free decay method. Design/methodology/approach: For the evaluation of the presumed effect experimental structural dynamic investigations comparing unidirectionally and fabric reinforced plastics are carried out. In detail the free decay behaviour of flat beamlike specimens under fixed-free boundary conditions and relatively constant and reproducible displacement excitation is investigated. Findings: The vibrating structure has been measured by a laser scanning vibrometer PSV 400 from POLYTEC. In both cases evaluation of the results yields enhanced damping properties of the specimens with fabric reinforcement compared to the unidirectionally reinforced specimens. The results justify the presumed acting of a mesomechanic kinematic. Research limitations/implications: The results show that in either case the material damping in terms of the logarithmic decrement of the fabric reinforced material is higher than the material damping in of the unidirectionally reinforced material. Additionally, when the fabric reinforced specimens are addressed, in each case the plain weave reinforced specimens exhibited higher values of the material damping as the twill weave 2/2 reinforced ones. Originality/value: Ondulations in fabrics as a textile semi-finished product are caused by the alternating crossing of warp and fill yarns. In the mesoscopic scale the acting of a mesomechanic kinematic is presumed to enhance the damping properties under cyclic elastic deformation. For the evaluation of the presumed effect experimental structural dynamic investigations comparing unidirectionally and fabric reinforced plastics are carried out. KW - structural vibration KW - damping KW - fibre reinforced plastics KW - mesomechanic scale KW - fabric reinforced layer Y1 - 2014 VL - 63 IS - 2 SP - 65 EP - 80 ER - TY - CHAP A1 - Jobst, Simon A1 - Bierl, Rudolf T1 - A Comparison of Correlation and Zero-Crossing Based Techniques in Ultrasonic Measurement T2 - 10th International Symposium on Applied Reconfigurable Computing (ARC'2014), Vilamoura, Algarve, Portugal, 14 - 16 April, 2014 N2 - Ultrasound measurement technology has advancedin previous decades due to positive developments in computing power and lower cost for the necessary hardware. Correlation-based processing can be advantageous for high-accuracy measurements, especially in noisy environments. Higher computational load makes correlation less attractive for industrialapplications, though, favouring traditional processing techniques. A platform for comparing various processing techniques hasbeen developed. It was found that both zero-crossing detectionas well as correlation can achieve very high accuracy over a hightemperature range but that correlation-based processing can lead to a significant precision bias depending on system bandwidth. Y1 - 2014 ER - TY - CHAP A1 - Hofmann, Matthias A1 - Bierl, Rudolf A1 - Rück, Thomas T1 - Implementation of a dual-phase lock-in amplifier on a TMS320C5515 digital signal processor T2 - Proceedings of the 5th European DSP Education and Research Conference (EDERC), 13-14 Sept. 2012, Amsterdam N2 - A digital dual-phase lock-in amplifier that is capable to run on a low-cost, low-power platform comprising a 16-bit fixed-point digital signal processor was developed. This is achieved by a set of optimised digital filters including an exponential averager to adjust the time constant of the overall filter. The reference frequency is generated using a direct digital synthesis source utilising angle decomposition with a resolution of 1 Hz. The digital lock-in algorithm is described and the performance of the algorithm is analysed. The experimental results show that the developed lock-in amplifier achieves similar performance to a commercially available lock-in amplifier. Y1 - 2012 U6 - https://doi.org/10.1109/EDERC.2012.6532217 ER - TY - CHAP A1 - Rück, Thomas A1 - Landgraf, Ferdinand A1 - Läpple, I. A1 - Unger, J. A1 - Matysik, Frank-Michael A1 - Bierl, Rudolf T1 - Specification of an improved photoacoustic setup for high-sensitive, low-cost NO2 trace gas detection T2 - 18th International Conference on Photoacoustic and Photothermal Phenomena (ICPPP18), 2015, September 6-10, Novi Sad, Serbia Y1 - 2015 ER - TY - CHAP A1 - van der Weerd, Bastiaan A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - A Conductivity Probe for the Determination of Carbon Dioxide Tension at the Oxygenator Exhaust Outlet during Extracorporeal Membrane Oxygenation (ECMO) T2 - analytica Conference 2014, 1. bis 4. April, München Y1 - 2014 ER - TY - CHAP A1 - van der Weerd, Bastiaan A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - A Conductivity Probe for the Determination of Carbon Dioxide Tension at the Oxygenator Exhaust Outlet during Extracorporeal Membrane Oxygenation (ECMO) T2 - Electrochemistry 2014, September 22 - 24, Mainz Y1 - 2014 ER - TY - CHAP A1 - van der Weerd, Bastiaan A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - A Planar Conductivity Probe for CO2 Determination at the Oxygenator Outlet T2 - Doktorandenseminar GDCh Prozessanalytik 2014, Berlin Y1 - 2014 ER - TY - CHAP A1 - Theuss, Horst A1 - Elian, Klaus A1 - Fink, Markus A1 - Fries, M. A1 - Kalz, Franz-Peter A1 - Schwabe, B. A1 - Vaupel, M. A1 - Jaroschek, C. A1 - Schubert, A. A1 - Hummel, H. A1 - Steffens, Oliver T1 - Mechanical Stress Impact of Assembly Processes onto a Stress-sensitive Testchip T2 - 44th International Symposium on Microelectronics (IMAPS 2011), October 9 - 13, 2011, Long Beach, California, USA N2 - A semiconductor die typically undergoes a variety of assembly processes, each of them influencing the mechanical stress environment of the chip. We report on a stress-sensitive testchip and its application to measure and characterize the respective stress distributions across the die. Particularly in the field of MEMS and sensor devices, even low stresses might deteriorate the electrical performance of a device significantly, while higher stress levels may even cause cracks and irreversible damage. This is why the present methodology has a high potential to develop into a useful tool in the field of sensor package development. After a brief introduction to the sensing principle, we investigate the stress distribution in various sample assemblies – all of them targeting pressure sensors. Typical low stress packages use silicone based soft elastic encapsulations. Changing to a harder material with a young’s modulus comparable to standard mold compounds, we demonstrate an increase of the average stress level by more than one order of magnitude. Y1 - 2011 SN - 978-1-61839-850-5 U6 - https://doi.org/10.4071/isom-2011-WA5-Paper3 IS - 1 SP - 619 EP - 626 PB - International Microelectronics & Packaging CY - Washington ER - TY - JOUR A1 - Malz, Sebastian A1 - Steininger, Peter A1 - Dawoud, Belal A1 - Krenkel, Walter A1 - Steffens, Oliver T1 - On the Development of a Building Insulation using Air Layers with Highly Reflective Interfaces JF - Energy and Buildings N2 - In this work, a novel building insulation system implying wooden fiberboards and intermediate air layers with highly reflective interfaces for the reflection of longwave IR radiation is introduced. A wall test sample with a double air insulation layer has been built and experimentally investigated in a dedicated setup, which consists of a differential climatic chamber to simulate different indoor and outdoor conditions. The test results have been utilized in validating the developed simulation model. In addition, a thorough numerical parameter study has been conducted, through which the general design rules of the introduced insulation system for realizing the lowest possible effective thermal conductivity have been defined. Furthermore, a multi-air-layer-insulation concept is developed, and the energy saving potential is evaluated. It turned out that, emissivity, object size and air layer thickness are the most dominant design parameters which influence the thermal conductivity of the introduced insulation. A thermal conductivity of 0.033 W/(mK) has been estimated for a multi-air-layer insulation with 7 layers. The obtained results prove the high insulation potential of the introduced building insulation system compared with insulating materials available in the market while outlining their limitations. KW - Building insulation KW - Infrared-reflective KW - Air layers KW - Energy-saving potential KW - Heat radiation Y1 - 2021 U6 - https://doi.org/10.1016/j.enbuild.2021.110779 IS - 236, April PB - Elsevier ER - TY - CHAP A1 - Steffens, Oliver A1 - Szabó, Peter A1 - Lenz, Michael A1 - Farkas, Gábor T1 - Thermal transient characterization methodology for single-chip and stacked structures BT - Best Paper Award T2 - Semiconductor Thermal Measurement and Management Symposium, 2005 N2 - High-power semiconductor packages typically exhibit a 3D heat flow, resulting in large lateral changes in chip and case surface temperature. For single-chip devices we propose to use an unambiguous definition for the junction-to-case thermal resistance as a key parameter, based on a transient measurement technique with much higher repeatability, also for very low thermal resistances compared to a two-point thermal resistance measurement. The technique is illustrated on thermal transient measurements of power MOSFETs. A comparison between different thermal coupling to the ambient is used to demonstrate the method's capability to reveal even subtle internal details of the package. The concept is extended to multichip and stacked-chip structures, where transfer impedances have to be introduced. Here, the dynamic properties of the package are important and complex impedance mapping is the proper way to characterize the package. KW - Thermal resistance KW - Temperature KW - Electrical resistance measurement KW - Impedance KW - Assembly KW - Semiconductor device packaging KW - Surface resistance KW - Measurement techniques KW - MOSFETs Y1 - 2005 U6 - https://doi.org/10.1109/STHERM.2005.1412198 SN - 1065-2221 SP - 313 EP - 321 PB - IEEE ER - TY - JOUR A1 - Puff, Simone A1 - Seidel, Uwe M. A1 - Steffens, Oliver T1 - Pflege- und intensivmedizinische Bereiche im EnEV-Bewertungsverfahren JF - Bauphysik N2 - Die Anwendbarkeit des derzeit gültigen Verfahrens zur energetischen Bewertung von Nichtwohngebäuden gemäß aktueller Energieeinsparverordnung (EnEV 2014) in Verbindung mit DIN V 18599 als Planungs- und Bewertungstool auf Pflege- und intensiv-medizinische Bereiche von Krankenhäusern wird an einem beispielhaften, mittelgroßen Krankenhaus untersucht. Der Fokus liegt dabei auf der Praktikabilität der Abbildung von thermischen Lasten und Raumzuständen durch die Normnutzungsprofile aus DIN V 18599 Teil 10 im Vergleich zu realen, vor Ort erfassten Nutzungsbedingungen. Weitere Betrachtungen in einer einfachen thermischen Simulation (TRNSYSlite) erlauben eine methodische Kritik in Bezug auf die Aussagekraft der nach Norm berechneten EnEV-Ergebnisse. Es werden Empfehlungen für Maßnahmen zur Verbesserung der energetischen Performance und der Behaglichkeit in Krankenhäusern im Bereich der Planung erarbeitet. T2 - Energetic Evaluation of care and critical care units of hospitals according to EnEV 2014 KW - Energieeinsparungsverordnung KW - Krankenhaus Y1 - 2015 U6 - https://doi.org/10.1002/bapi.201510036 VL - 37 IS - 6 SP - 307 ER - TY - JOUR A1 - Wensauer, Andreas A1 - Steffens, Oliver A1 - Suhrke, Michael A1 - Rössler, Ulrich T1 - Laterally coupled few-electron quantum dots JF - Physical Review B N2 - We present ground-state calculations for laterally coupled quantum dots containing 2, 4, and 8 electrons. As our emphasis is on spin effects our results are obtained by applying spin-density functional theory (SDFT). By varying the distance between the centers of the coupled quantum dots, the transition from weak to strong coupling situation is realized. For the 2-electron system we also apply the Heitler-London approximation and analytical concepts to check the reliability of SDFT calculations in this case. In addition we discuss the features of the Coulomb staircase of laterally coupled quantum dots in the weak and strong coupling regimes in comparison to that of a circular parabolic quantum dot. Y1 - 2000 U6 - https://doi.org/10.1103/PhysRevB.62.2605 VL - 62 IS - 4 SP - 2605 ER - TY - CHAP A1 - Steffens, Oliver ED - Trapp, Eugen T1 - "Grünes Denkmal" - Denkmalpflege und Erneuerbare Energien ergänzen sich T2 - Vorsicht Baudenkmal! Konfliktfelder Umwelt - Nutzung - Geschichte. Beiträge des 28. Regensburger Herbstsymposions für Kunst, Geschichte und Denkmalpflege vom 22. bis 24. November 2013 KW - Denkmalpflege KW - Denkmalschutz KW - Erneuerbare Energien Y1 - 2014 SN - 978-3-937527-77-2 SP - 9 EP - 17 PB - Regensburg CY - Morsbach-Verl. ER - TY - CHAP A1 - Steffens, Oliver A1 - Suhrke, Michael A1 - Rössler, Ulrich ED - Gershoni, David T1 - Correlation in few-electron quantum dots: Spin effects and spontaneous currents T2 - 24rd International Conference on the Physics of Semiconductors (ICPS 24), Jerusalem, Israel, August 2-7, 1998 Y1 - 1999 SN - 978-981-02-3613-7 PB - World Scientific CY - Singapore ER - TY - THES A1 - Gering, Stefan T1 - Thermische Detailsimulationen in der Bestandssanierung Y1 - 2014 CY - Regensburg ER - TY - JOUR A1 - Szabó, Peter A1 - Steffens, Oliver A1 - Lenz, Michael A1 - Farkas, Gábor T1 - Transient junction-to-case thermal resistance measurement methodology of high accuracy and high repeatability JF - IEEE Transactions on Components and Packaging Technologies N2 - High-power packages show a characteristic three-dimensional heat flow resulting in large lateral changes in chip and case surface temperature. This paper proposes an unambiguous definition for the R/sub thJC/ junction-to-case thermal resistance as a key parameter of such packages based on a transient measurement technique ensuring high repeatability even at very low R/sub th/ values. The technique is illustrated on thermal transient measurements of high-power MOSFET devices. It is also presented how the same measurement results can be used for die attach quality analysis. Finally, a comparative method is shown for measuring the differences of R/sub th/ values among samples with many times higher resolution compared with a direct R/sub thJC/ measurement. KW - Thermal resistance KW - Electrical resistance measurement KW - Temperature KW - Packaging KW - Cold plates KW - MOSFET circuits KW - Semiconductor device measurement KW - Surface resistance KW - Microassembly KW - Thermal conductivity Y1 - 2005 U6 - https://doi.org/10.1109/TCAPT.2005.859768 SN - 1521-3331 VL - 28 IS - 4 SP - 630 EP - 636 ER - TY - JOUR A1 - Mayrock, Oliver A1 - Mikhailov, Sergej A. A1 - Steffens, Oliver A1 - Rössler, Ulrich T1 - Observability of the acoustic plasma mode in double-layered quantum dots JF - Physica E: Low-dimensional Systems and Nanostructures N2 - Double-layered quantum dots represent a novel realization of a multi-component plasma system. By modelling the system and applying classical concepts we investigate the oscillator strength of the acoustic plasma mode and its dependence on the system parameters. In view of recent experimental results, we discuss the observability of this collective excitation. KW - Quantum dots KW - Collective excitations KW - Magneto-plasmon KW - Acoustic modes Y1 - 1997 U6 - https://doi.org/10.1016/S1386-9477(97)00048-9 VL - 1 IS - 1-4 SP - 232 EP - 234 ER - TY - GEN A1 - Köhler, Ann-Kathrin A1 - Ostermeier, Nadine A1 - Schaubächer, Ursula A1 - Wolf, Lars T1 - Einfluss der Wärmespeicherfähigkeit von Massivbauteilen auf den Heizwärmebedarf und die Behaglichkeit eines Gebäudes BT - Literaturstudie. Masterprojektarbeit KW - Wärmespeicherung KW - Massivbau KW - Energieeinsparung KW - Behaglichkeit KW - Gebäude Y1 - 2015 CY - Regensburg ER - TY - RPRT A1 - Schaubeck, Simon A1 - Steffens, Oliver A1 - Rechenauer, Christian T1 - Integration eines kostenoptimierten, wirtschaftlich rentablen Blockheizkraftwerks mit mittlerer thermischer Leistung in ein genossenschaftliches Wohnquartier BT - TWO-Projekt (Technologie- und Wissenschaftsnetzwerk Oberpfalz), Endbericht 08 / 2015 Y1 - 2015 ER - TY - CHAP A1 - Rechenauer, Christian A1 - Neuleitner, Nikolaus A1 - Steffens, Oliver T1 - Empirische Untersuchung und Optimierung der Performance eines Modellprojekts für ein Effizienzhaus Plus mit solarthermischem Energiekonzept T2 - Fachforum Effizienzhaus Plus, 14.07.2015 Y1 - 2015 CY - Hamburg ER - TY - BOOK A1 - Steffens, Oliver T1 - Einfluss der Potentialmodulation auf Magnetotransport und Quantenchaos in lateralen Halbleiter-Übergittern Y1 - 1996 SN - 978-3-89608-726-3 N1 - Mikrofiche-Ausg. PB - Tectum-Verl. CY - Marburg ER - TY - RPRT A1 - Steffens, Oliver T1 - Saisonale Wärmespeicherung von opaken Bauteilen im Massivbau BT - Literatur-Übersicht Y1 - 2015 ER - TY - JOUR A1 - Raith, Lea A1 - Schmidling, Anja A1 - Windisch, Bastian T1 - Bauteiltemperierung BT - Studienarbeit Y1 - 2012 CY - Regensburg ER - TY - JOUR A1 - Steffens, Oliver A1 - Suhrke, Michael A1 - Rotter, Peter A1 - Rössler, Ulrich T1 - From Landau levels to universal fluctuations: Level statistics for lateral superlattices JF - Physical Review B N2 - We study the energy-level statistics for electrons in a lateral two-dimensional superlattice in dependence on the strength of the modulation potential at a given perpendicular magnetic field. The interminiband statistics at some selected point in the magnetic Brillouin zone shows a transition from degenerate Landau levels to universal spectral correlations while the corresponding classical dynamics displays a crossover from regular cyclotron orbits to chaotic motion. In terms of the nearest-neighbor spacing distribution, we observe the occurrence of level repulsion for all nonzero modulation amplitudes, which indicates a discontinuous transition to universal fluctuations for the smallest level spacings when the rotational invariance of the system is broken by a finite superlattice potential. In order to test the universality of the transition on larger scales, we propose a random matrix model with one transition parameter for comparison. Confirmed by two different types of potential shapes, we detect an explicit influence of the potential shape on the level spacing distributions, which hence cannot be described by the one-parameter model. Using the spectral rigidity, however, universal long-range fluctuations in the regime of negligible Landau-level mixing are found, in agreement with our random matrix model. Y1 - 1997 U6 - https://doi.org/10.1103/PhysRevB.55.4486 VL - 55 IS - 7 SP - 4486 EP - 4493 ER - TY - JOUR A1 - Steffens, Oliver A1 - Wensauer, Andreas A1 - Suhrke, Michael T1 - Collective excitations in quantum dots: Calculated Raman spectra JF - physica status solidi (b) N2 - Electronic Raman scattering provides information on excited states, whose collective character as being related to the charge or spin density can be distinguished by using different polarization configurations. We employ time-dependent spin-density functional theory to calculate Raman spectra for circular semiconductor quantum dots with up to 10 electrons for the polarized and depolarized configuration and in dependence on an external magnetic field and the momentum transfer. Our results demonstrate an increase of the collective (or many-particle) character of the excitations with increasing momentum transfer and a mixing of spin- and charge-density modes for excitations from ground states with finite spin density. These results have predictive character, because corresponding experiments on few-electron dots have not yet been performed. Y1 - 1999 U6 - https://doi.org/10.1002/(SICI)1521-3951(199909)215:1<365::AID-PSSB365>3.0.CO;2-C VL - 215 SP - 365 EP - 371 PB - Wiley ER - TY - JOUR A1 - Suhrke, Michael A1 - Steffens, Oliver A1 - Rotter, Peter A1 - Rössler, Ulrich T1 - Quantum chaos and magnetotransport in lateral superlattices: The transition from weak to strong modulation potential JF - Physica E: Low-dimensional Systems and Nanostructures N2 - Magnetotransport in lateral superlattices covers a variety of apparently different physics dependent on the amplitude of the modulation potential relative to the Fermi energy ranging from the weakly modulated 2DEG to the antidot lattice. Here we investigate the transition between weak modulation and antidots within the quantum-mechanical theory by studying (i) the single-particle spectrum with respect to quantum signatures of classical chaos and (ii) the change of characteristic features in the magnetoresistance starting from the Kubo formula. KW - Lateral superlattices KW - Quantum chaos KW - Level statistics KW - Magnetotransport KW - Commensurability oscillations Y1 - 1997 U6 - https://doi.org/10.1016/S1386-9477(97)00060-X SN - 1386-9477 VL - 1 IS - 1-4 SP - 281 EP - 287 ER - TY - RPRT A1 - Steffens, Oliver A1 - Rössler, Ulrich A1 - Suhrke, Michael T1 - Comment on "Shell Filling and Spin Effects in a Few Electron Quantum Dot" T2 - Physical Review Letters N2 - We briefly report on calculated addition spectra for electrons in a circular quantum dot with perpendicular magnetic field. We compare our current density functional theory calculations with recent experiments by Tarucha et al. [PRL 77, 3613 (1996)]. We find a very good qualitative agreement of the structures and find an additional effect caused by Hund's first rule in magnetic field, which gives rise to new substructures not discussed in the paper by Tarucha. Y1 - 1996 UR - http://arxiv.org/abs/cond-mat/9711077 VL - 77 SP - 3613 ER - TY - JOUR A1 - Steffens, Oliver T1 - Energetische Modernisierung und Restaurierung historisch wertvoller Stadtquartiere. Regenerative Energieversorgung als Schwerpunkt einer nachhaltigen Modernisierung historisch wertvoller Stadtquartiere (RENARHIS) JF - Zukunft bauen. Forschungsinitiative Zukunft Bau 2016 Y1 - 2016 IS - 5 SP - 62 EP - 65 PB - Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit (BMUB) ER - TY - GEN A1 - Steffens, Oliver A1 - Saller, Tobias T1 - Modernisierungskonzepte für das denkmalgeschützte Ensemble am Jahn-Stadion Regensburg Prüfeninger Straße 47–52 BT - Studiengang Gebäudeklimatik. Studienarbeiten Y1 - 2014 ER - TY - RPRT ED - Neuleitner, Nikolaus ED - Steffens, Oliver T1 - Energienutzungsplan für die Gemeinde Sinzing BT - Phase I. Bestandsaufnahme. Ergebnisbericht 1 (12/2011) Y1 - 2011 ER - TY - CHAP A1 - Gerhards, Helene ED - Mauer, Heike ED - Leinius, Johanna ED - Gerhards, Helene T1 - Von Patient*innenzellen und Patient*innenzahlen BT - Intersektionale Perspektiven auf biomedizinische Forschung T2 - Intersektionalität und Postkolonialität ; kritische feministische Perspektiven auf Politik und Macht Y1 - 2021 SN - 9783847424550 U6 - https://doi.org/10.3224/84742455 SP - 181 EP - 203 PB - Verlag Barbara Budrich CY - Opladen; Berlin ER - TY - JOUR A1 - Hartmann, Julia A1 - Heckner, Markus A1 - Plach, Ulrike T1 - Future Skills bei Studierenden – Messung und Einflussfaktoren JF - Die Neue Hochschule N2 - Eine sich stetig verändernde Arbeitswelt erfordert neue Kompetenzen von unseren Studierenden. In der Lehre gilt es nicht nur, diese Zukunftskompetenzen (sog. Future Skills) zu fördern, sondern diese auch zu messem und sichtbar zu machen. KW - Future Skills KW - Studierende Y1 - 2023 UR - https://www.yumpu.com/de/document/read/68553002/die-neue-hochschule-heft-6-2023 IS - 6 SP - 24 EP - 27 ER - TY - GEN A1 - Hartmann, Julia A1 - Heckner, Markus A1 - Plach, Ulrike T1 - Einfluss studierendenzentrierter Lehrelemente auf die Entwicklung von Zukunftskompetenzen bei Studierenden KW - Future Skills KW - Lehrkonzepte Y1 - 2023 ER - TY - GEN A1 - Hartmann, Julia T1 - Der Einfluss verschiedener Lehr-Lern-Formate auf das studentische Engagement und die Entwicklung von Future Skills bei Studierenden KW - Future Skills KW - Lehr-Lern-Formate Y1 - 2024 ER - TY - JOUR A1 - Koenig, Eric A1 - Guertler, Katherine T1 - One Size Does Not Fit All: Individuality and Perceptions of Improvement and Satisfaction Among TE Students JF - English Teaching & Learning N2 - Academic self-regulation is a key factor for motivation and learning achievement. Yet with the large range of individual factors, this is not a one-size-fits-all proposition. This study of L2 Technical English students at two German universities explored learners’ expectations and motivations, in particular regarding self-regulation and self-efficacy via the individual’s time investment in self-led study. In an initial survey, learners (N=1646) reported on their English skill levels and anticipated learning habits. Complementarily, the retrospective survey investigated learners’ (N=796) actual behavior during the course, their perceptions of language skill improvement, and their satisfaction. The initial survey indicates a clear understanding that time investment in self-regulated study will lead to greater improvement, an outcome confirmed in the retrospective survey. Additionally, students who invested more time in their coursework were more satisfied with their achievement, although most learners acknowledge they should have studied more. The results verify that learners recognize the nexus between self-regulation and language skill improvement, yet university students are not satisfied with their capacity to self-regulate their language learning strategies. While differences in students’ skill levels and academic self-efficacy result in divergent degrees of progress, students of all types report benefits to their language skills when motivated to self-regulated study. Y1 - 2021 U6 - https://doi.org/10.1007/s42321-021-00076-4 VL - 45 IS - 3 SP - 303 EP - 324 PB - Springer Nature ER - TY - JOUR A1 - Yeap, Kim Ho A1 - Meister, Tobias A1 - Oh, Zi Xin A1 - Nisar, Humaira T1 - Circuit Modelling Methodology for Dual-band Planar Antennas JF - APPLIED COMPUTATIONAL ELECTROMAGNETICS SOCIETY JOURNAL N2 - This paper presents a simple and systematic approach to determine the equivalent frequency-independent circuit model for a dual-band planar antenna. The Foster Canonical network synthesis technique with two RLC tanks has been employed to generate the two resonant bands of the antenna. The transfer function model is subsequently refined using a data fitting algorithm (viz the Nelder-Mead simplex algorithm). Parametric adjustments are performed at the final stage in order to further improve the accuracy of the final parameters. KW - COMPACT KW - Data-fitting algorithm KW - equivalent circuit KW - Foster canonical network KW - PATCH KW - planar antenna KW - resonant bands KW - SHAPED ANTENNA Y1 - 2021 U6 - https://doi.org/10.47037/2021.ACES.J.360822 VL - 36 IS - 8 SP - 1112 EP - 1115 PB - APPLIED COMPUTATIONAL ELECTROMAGNETICS SOC ER - TY - JOUR A1 - Li, Shisong A1 - Stock, Michael A1 - Schlamminger, Stephan T1 - A new magnet design for future Kibble balances JF - Metrologia N2 - We propose a new permanent magnet system for Kibble balance experiments, which combines advantages of the magnet designs invented by the National Physical Laboratory (NPL) and by the Bureau International des Poids et Mesures (BIPM). The goal of the proposed magnet system is to minimize the coil-current effect and to optimize the shielding at the same time. In the proposed design, a permanent magnet system with two gaps, each housing a coil, is employed to minimize the coil current effect, by reducing the linear coil-current dependence reported for the single air gap design by at least one order of magnitude. Both air gaps of the magnet are completely surrounded by high-permeability material, and hence the coils are shielded from outside magnetic fields and no magnetic field leaks outside of the magnet system. An example of the new magnet system is given and the analysis shows that the magnetic field in the air gap can be optimized to meet the requirement to be used in Kibble balances. KW - II WATT BALANCE KW - inductance force KW - JOULE BALANCE KW - Kibble balance KW - magnetic field KW - magnetic shielding KW - MARK-II KW - NATIONAL INSTITUTE KW - NIM KW - PLANCK CONSTANT KW - standards KW - SYSTEM KW - TECHNOLOGY Y1 - 2018 U6 - https://doi.org/10.1088/1681-7575/aab2ea VL - 55 IS - 3 SP - 319 EP - 325 PB - IOP PUBLISHING ER - TY - JOUR A1 - Schreiner, Rupert A1 - Langer, Christoph A1 - Prommesberger, Christian A1 - Dams, Florian T1 - Compact and Energy-Efficient Field Emission Cathodes for Sensor Applications JF - Advanced Materials Research N2 - We report on miniaturized silicon field emitter arrays for the application in compact and energy-saving vacuum-microelectronic devices, e.g. sensors or x-ray tubes. Since standard silicon semiconductor technology has been used for the fabrication, they may be easily integrated with other silicon based circuits and devices on the same chip. The silicon tip geometry and the operating conditions were optimized in order to obtain highly uniform and stable electron field emission from large area cathode arrays. A series of uniform hexagonal tip arrays containing each 547 tips were fabricated and characterized. The electron emission properties of both individual tips as well as of complete emitter arrays were investigated. A saturation level in the voltage-current characteristics was found, which can be explained by the limitation of the supply of electrons due to the p-type silicon wafer material. When operating the arrays in the current saturation regime at an emission current of ~ 1 nA per tip, a highly stable and low noise emission can be observed. KW - field emission KW - Si-Tip Cathodes KW - Vacuum Sensors Y1 - 2014 U6 - https://doi.org/10.4028/www.scientific.net/amr.1024.372 VL - 1024 SP - 372 EP - 375 PB - Scientific.net ER - TY - JOUR A1 - Chee, See Wee A1 - Kammler, Martin A1 - Graham, Jeremy A1 - Gignac, Lynne A1 - Reuter, Mark C. A1 - Hull, Robert A1 - Ross, Frances M. T1 - Directed Self-Assembly of Ge Quantum Dots Using Focused Si2+ Ion Beam Patterning JF - scientific reports N2 - We show that templating a Si surface with a focused beam of Si2+ or Si+ ions can create suitable nucleation sites for the subsequent growth of self-assembled Ge quantum dots by chemical vapor deposition. To determine the mechanism of patterning we use atomic force microscopy to show that, similar to Ga+ patterning, the formation of a surface pit is required to enable control over Ge quantum dot locations. We find that relatively high implantation doses are required to achieve patterning, and these doses lead to amorphization of the substrate. We assess the degree to which the substrate crystallinity can be recovered by subsequent processing. Using in situ transmission electron microscopy heating experiments we find that recrystallization is possible at the growth temperature of the Ge quantum dots, but defects remain that follow the pattern of the initial implantation. We discuss the formation mechanism of the defects and the benefits of using Si ions for patterning both defects and quantum dots on Si substrates. KW - ARRAYS KW - AU KW - DAMAGE KW - GROWTH KW - IMPLANTATION KW - NUCLEATION KW - RECOVERY KW - silicon KW - TECHNOLOGY Y1 - 2018 U6 - https://doi.org/10.1038/s41598-018-27512-z VL - 8 SP - 1 EP - 10 PB - Nature ER - TY - JOUR A1 - Schnitzer, Susanne A1 - Richter, Stefanie A1 - Walter, Andreas A1 - Balke, Klaus A1 - Kuhlmey, Adelheid T1 - Die Bewertung der ambulanten Gesundheitsversorgung aus Versichertensicht BT - Ergebnisse der KBV-Befragung 2008 – Teil 1 JF - Gesundheits- und Sozialpolitik N2 - In den letzten Jahren haben verschiedene Institutionen bevölkerungsrepräsentative Befragungen zur Bewertung von Einzelaspekten der Gesundheitsversorgung durchgeführt (Bertelsmann Gesundheitsmonitor, Commonwealth Fund, Gesundheitssurvey des Robert Koch-Instituts, BKK-Befragung, WIdO-monitor). Hierzu zählt auch die Kassenärztliche Bundesvereinigung (KBV), die im Jahr 2006 die Forschungsgruppe Wahlen Telefonfeld (FGW) in Mannheim beauftragte, repräsentativ gesetzlich und privat Versicherte zur Zufriedenheit mit der ambulanten Versorgung sowie zum Bedarf an neuen Dienstleistungsangeboten zu befragen (KBV 2006; Rieser 2006). Eine zweite Versichertenbefragung der KBV erfolgte im Zeitraum Mai und Juni 2008, wiederum von der FGW durchgeführt. Die Ergebnisse dieser repräsentativen Erhebung werden im Rahmen von zwei Artikeln in Gesundheits- und Sozialpolitik vorgestellt. Im Zentrum des hier vorliegenden ersten Beitrags stehen die Inanspruchnahme der ambulanten haus- und fachärztlichen Versorgung, die Erfahrungen mit Terminvergabe und Wartezeiten sowie die Bewertungen der Versorgung durch die Versicherten. Darüber hinaus wird die Bedeutung von Individuellen Gesundheitsleistungen (IgeL) in der ambulanten Versorgung gesetzlich Versicherter diskutiert. Der zweite Artikel wird sich schwerpunktmäßig mit den Qualitätskriterien für die Wahl eines Arztes, mit den Erfahrungen von Veränderungen in der Medikamentenverordnung sowie mit der Akzeptanz neuer Versorgungsformen und Wahltarife befassen. Y1 - 2008 UR - https://www.jstor.org/stable/26766864 VL - 62 IS - 5 SP - 11 EP - 20 PB - Nomos ER - TY - JOUR A1 - Schnitzer, Susanne A1 - Richter, Stefanie A1 - Walter, Andreas A1 - Balke, Klaus A1 - Kuhlmey, Adelheid T1 - Die Bewertung der ambulanten Gesundheitsversorgung aus Versichertensicht BT - Ergebnisse der KBV-Befragung 2008 – Teil 2 JF - Gesundheits- und Sozialpolitik N2 - In der Ausgabe 5/2008 von „Gesundheits- und Sozialpolitik“ wurden erste Ergebnisse der zweiten Versichertenbefragung der Kassenärztlichen Bundesvereinigung (KBV) vorgestellt. Der Fokus der Darstellung lag im ersten Teil auf dem Inanspruchnahmeverhalten und der Zufriedenheit der Versicherten mit der ärztlichen Versorgung, wobei der Aspekt der Wartezeiten auf einen Termin und in der Arztpraxis ausführlich behandelt wurde. Insgesamt ist eine hohe Inanspruchnahme der haus- und fachärztlichen ambulanten Versorgung zu konstatieren sowie eine überwiegende Zufriedenheit mit der ärztlichen Betreuung. Die Ergebnisse zu den Wartezeiten auf einen Arzttermin spiegeln im Vergleich zu öffentlich geführten Debatten ein differenziertes Bild wider. Im zweiten Teil werden folgende Fragen vertiefend diskutiert: Welche Kriterien sind neben der fachlichen Kompetenz (für die Versicherten) für die Wahl der Arztpraxis relevant? Welche Bedeutung haben Gütesiegel als Qualitätsmarker für die Versicherten? Welche Erfahrungen haben die Versicherten mit Änderungen in der Medikamentenverordnung gemacht? Nehmen die Versicherten an Hausarztmodellen teil und wie bewerten sie die Versorgungsqualität? Welche Akzeptanz haben unterschiedliche Wahltarife bei den gesetzlich Versicherten? Y1 - 2008 UR - https://www.jstor.org/stable/26766877 VL - 62 IS - 6 SP - 19 EP - 27 PB - Nomos ER - TY - JOUR A1 - Balke, Klaus A1 - Schnitzer, Susanne A1 - Walter, Andreas A1 - Richter, Stefanie A1 - Kuhlmey, Adelheid T1 - Wartezeit ist ein wichtiges Kriterium bei der Wahl der Arztpraxis JF - Deutsches Ärzteblatt N2 - Ältere Patienten und Frauen warten länger auf einen Arzttermin als junge Versicherte und Männer, gesetzlich Versicherte länger als Privatpatienten. Die meisten Patienten sind aber keineswegs unzufrieden. 90 Prozent bekommen entweder am selben Tag einen Termin oder halten die Wartezeit für angemessen. Y1 - 2008 UR - https://www.aerzteblatt.de/pdf.asp?id=61240 VL - 105 IS - 34-35 SP - A1766 EP - A1768 PB - Deutscher Ärzteverlag ER - TY - CHAP A1 - Hausladen, Matthias A1 - Bomke, Vitali A1 - Buchner, Philipp A1 - Bachmann, Michael A1 - Knapek, Alexandr A1 - Schreiner, Rupert T1 - Influence of Geometrical Arrangements of Si Tip Arrays Fabricated by Laser Micromachining on their Emission Behaviour T2 - 2021 34th International Vacuum Nanoelectronics Conference (IVNC): 7/5/2021 - 7/9/2021, Lyon, France N2 - ensely packed emitters on a field emission array lead typically to mutual shielding. Taking biology as a role model for geometric arrangements could be a way to reduce this effect. For comparison, two electron sources, one with a spiral and a second with conventional rectangular (orthogonal) arranged emitters, were fabricated and investigated. Emission currents of 6 µA in the spiral ordered array and 120 µA in the rectangular array were reached with an extraction voltage of 400 V. From a mid-term measurement over 1 h a current stability of ±8.8 % (spiral) respectively ±5.7 % (rectangular) with a mean degradation of -3.0 µA/h (spiral) and -0.12 µA/h (rectangular) could be observed. KW - aperture field KW - emission grid KW - Fabrication KW - laser micromachining KW - parastichy tip arrangements KW - silicon field emission KW - Stability analysis KW - Spirals KW - Field emitter array KW - Voltage measurement Y1 - 2021 SN - 978-1-6654-2589-6 U6 - https://doi.org/10.1109/IVNC52431.2021.9600717 SN - 2380-6311 PB - IEEE CY - Piscataway, N.J. ER - TY - CHAP A1 - Buchner, Philipp A1 - Bomke, Vitali A1 - Hausladen, Matthias A1 - Edler, Simon A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Investigation on the Emission Behaviour of p-doped Silicon Field Emission Arrays with Individually Controllable Single Tips T2 - 2021 34th International Vacuum Nanoelectronics Conference (IVNC): 7/5/2021 - 7/9/2021, Lyon, France N2 - Four individually controllable emission tips consisting of <111> p-Type silicon, were structured on a glass substrate by laser ablation. A matching extraction grid was manufactured in the same manner and aligned with the emitters. The resulting samples were characterized in ultra-high vacuum. As expected, the individual currents show a strong saturation and in the saturation region a considerably lower current fluctuation than n-type silicon due to charge carrier depletion. The individual tips behave completely independent behaviour from each other and the overall emission can be deduced from the sum of the currents through the individual tips. Y1 - 2021 SN - 978-1-6654-2589-6 U6 - https://doi.org/10.1109/IVNC52431.2021.9600756 SP - 1 EP - 2 PB - IEEE ER - TY - CHAP A1 - Hecht, Fabian A1 - Bauereiβ, Florian A1 - Sellmair, Josef A1 - Buchner, Philipp A1 - Hausladen, Matthias A1 - Schreiner, Rupert T1 - Electron Beam Induced Growth of Carbon Nanotips on Tungsten and Silicon Fieldemitters T2 - 2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA N2 - In our experiments we grew electron emitting carbon nanostructures on tungsten tips. Subsequently, we transferred the growth process to pre-structured phosphorus-doped n-type silicon and obtained emitting carbon nanostructures directly grown on silicon. After growth of the nanostructures, the silicon field emitters showed increased emission currents of 76 nA at 1.1 kV (compared to 6 nA under the same conditions before growth). KW - Behavioral sciences KW - Nanostructures KW - Silicon KW - Carbon dioxide KW - Current measurement KW - Electron beams KW - Tungsten Y1 - 2023 SN - 979-8-3503-0143-4 U6 - https://doi.org/10.1109/IVNC57695.2023.10188960 SP - 160 EP - 162 PB - IEEE ER -