HTS pulse-stretcher and second order modulator: design and first results

One of the remaining challenges in the application of superconducting electronics is the interfacing between superconducting and semiconducting environments. The voltage and speed mismatch between RSFQ pulses and semiconducting read-out electronics makes it necessary to amplify as well as stretch the RSFQ pulses. Moreover, circuits based on HTS (High Temperature Superconductor) technology are very attractive since they can operate under considerably relaxed cooling effort, which is one of the main problems with LTS (Low Temperature Superconductor) circuits. Within the European project SuperADC, a HTS second order sigma delta modulator and a pulse stretcher, used as an interface between the modulator and the first semi-conducting amplifier stage, have been designed at Twente University and will be presented here

RSFQ Circuitry Using Intrinsic π-Phase Shifts

The latching of temporary data is essential in the rapid single flux quantum (RSFQ) electronics family. Its pulse-driven nature requires two or more stable states in almost all cells. Storage loops must be designed to have exactly two stable states for binary data representation. In conventional RSFQ such loops are constructed to have two stable states, e.g. by using asymmetric bias currents. This bistability naturally occurs when phase-shifting elements are included in the circuitry, such as pi-Josephson junctions or a pi-phase shift associated with an unconventional (d-wave) order parameter symmetry. Both approaches can be treated completely analogously, giving the same results. We have demonstrated for the first time the correct operation of a logic circuit, a toggle-flip-flop, using rings with an intrinsic pi-phase shift (pi-rings) based on hybrid high-Tc to low-Tc Josephson junctions. Because of their natural bistability these pi-rings improve the device symmetry, enhance operation margins and alleviate the need for bias current lines.\ud \u

Bildungstheoretisch orientierte Internetarbeit am Beispiel der universitären Lehre

Die Autoren gehen der Frage nach, welche bildungstheoretischen Ansprüche an die Informationsgesellschaft zu stellen sind. Eingangs stellen sie die These vor, dass sich Wissen in Verfügungs- und Orientierungswissen unterscheiden lässt, wobei ersteres das Verfügen über faktische Informationen, das letztere die Fähigkeit zur Strukturierung von Wissen bedeutet. Die bloße Vermehrung von Verfügungswissen führt nicht automatisch zur Anreicherung des Orientierungswissens, es muss vielmehr erworben werden. Eine Wissensgesellschaft muss drei Voraussetzungen erfüllen: Informationen in Wissen transformieren, einen reflektierten Umgang mit diesem Wissen anstreben und dem Einzelnen die Möglichkeit zur Artikulation im öffentlichen Raum gewährleisten. Im Anschluss an den Theoriediskurs präsentieren die Autoren die Anwendung an Internetprojekten, die an der Universität Magdeburg durchgeführt wurden. Hier zeigte sich die Notwendigkeit zur problemorientierten Arbeit: die Komplexität des verfügbaren Wissens im Netz ist im Hinblick auf die Fragestellung zu reduzieren und zu strukturieren. Im Zeitalter der Informationsflut sind Vergleiche und Überprüfungen von Quellen unerlässlich. Die Artikulation im öffentlichen Raum wurde dadurch gewährt, dass Studierende die Ergebnisse ihrer Arbeiten im Internet persönlich gekennzeichnet präsentierten

Decoherence in a superconducting flux qubit with a pi-junction

We consider the use of a pi-junction for flux qubits to realize degenerate quantum levels without external magnetic field. On the basis of the Caldeira-Leggett model, we derive an effective spin-Boson model, and study decoherece of this type of qubits. We estimate the dephasing time by using parameters from recent experiments of SIFS junctions, and show that high critical current and large subgap resistance are required for the pi-junction to realize a long coherent time.Comment: 5 pages, 2 figure

Dissipative current in SIFS Josephson junctions

We investigate superconductor/insulator/ferromagnet/superconductor (SIFS) tunnel Josephson junctions in the dirty limit, using the quasiclassical theory. We consider the case of a strong tunnel barrier such that the left S layer and the right FS bilayer are decoupled. We calculate quantitatively the density of states (DOS) in the FS bilayer for arbitrary length of the ferromagnetic layer, using a self-consistent numerical method. We compare these results with a known analytical DOS approximation, which is valid when the ferromagnetic layer is long enough. Finally we calculate quantitatively the current-voltage characteristics of a SIFS junction.Comment: Proceedings of the Vortex VI conference, to be published in Physica

Causes, consequences and countermeasures of overtaking accidents on two-lane rural roads

Overtaking accidents have one of the most serious consequences of accidents on German rural roads. The aim of this project was to determine the infrastructural and traffic related variables which influence the occurrence and consequences of overtaking accidents as well as the overtaking behavior of drivers. Finally, diverse correlations between operational and infrastructural road characteristics and overtaking accidents and driver behavior were found out and a catalogue of measures had been developed. The given recommendations will have beneficial influences on overtaking behavior and their practice will lead to an increase in safety on two-lane rural roads

Влияние вибрации на проникновение жидкости в капилляре

Объектом исследования является влияние вибрации на проникновение дефектоскопических материалов для капиллярного контроля.В процессе выполнения работы проводились теоретические исследования изучаемой темы; исследование проникающей способности жидкостей при нормальных условиях, а так же при воздействии температуры и вибрации.The object of study is the effect of vibration on the penetration of the penetrant testing materials for liquid penetrant inspection.During execution of the work carried out theoretical studies of the subject; study on penetration of liquids under normal conditions and when exposed to temperature and vibration