Cost-Benefit Analysis for the Selection, Migration, and Operation of a Campus Management System

An increasing number of students, together with organizational and technological requirements, pose new challenges for universities. For these reasons, Campus Management Systems provide a solution for the necessary IS-support in student administration. In order to ensure cost-effectiveness, an extensive cost-utility analysis of the campus management systems under consideration is required. The process model illustrated here facilitates a ten-step cost-utility analysis for the selection, migration and operation of a campus management System. The process-oriented approach addresses the challenges posed by cost and benefit allocation. The subsequent ten steps, using the case analysis of two large German universities, show that the implementation of an integrated campus management system can lead to significant cost saving effects. The presented process model enables comparative calculations of differences with regard to the alternatives. The approach enables a comprehensive decision-support system for the selection of a university-specific and individually applicable campus management system

Discussion and Validation of a CRM System Selection Approach with Experts

Due to the high failure rate, costs, and long duration of CRM implementation projects, it is crucial to evaluate softwaresolutions before making an investment decision. A methodological approach is required to make these decisions moreeffectively and efficiently. In this paper, an approach to evaluating CRM software packages is proposed that is the result of aliterature review. In a second step, an initial applicability check of the approach is conducted. The intention is to verify thefeasibility of the proposed approach with CRM experts who have practical experience with the selection of different systems.An empirical study that is subdivided into qualitative expert interviews and a quantitative online survey is used for thisverification. The core results demonstrate that the approach is a valid method for evaluating CRM software applications

Untersuchung des Dreipunkt – Neutral Point Clamped – Stromrichters mit Spannungszwischenkreis (3L-NPC-VSC) für Niederspannungswindkraftanwendungen

Das Ziel der Arbeit war die Untersuchung eines neuartigen Phasenbausteins mit der Topologie des Dreipunkt – Neutral Point Clamped – Stromrichters mit Spannungszwischenkreis (3L-NPC-VSC) für Windkraftanwendungen. Wichtige Anforderungen an den Phasenbaustein und daraus resultierende Herausforderungen, sowie Lösungen für ausgewählte Teilprobleme werden präsentiert. Um die Vorteile des 3L-NPC-VSC für Hersteller von Windkraftanlagen zugänglich zu machen, ist es sinnvoll, einen neuartigen Phasenbaustein zu entwickeln. Der Phasenbaustein soll einfach in Systeme zu integrieren sein, in denen gegenwärtig Zweipunktstromrichter (2L-VSC) zum Einsatz kommen. Da sich Modulation, Zwischenkreisbalancierung und Kurzschlussschutz vom 2L-VSC unterscheiden, soll der Phasenbaustein diese Herausforderungen eigenständig bewältigen. Die Arbeit beschreibt die Konzeption eines solchen Phasenbausteins und behandelt insbesondere die Modulation, die Zwischenkreisbalancierung und den Kurzschlussschutz des 3L-NPC-VSC. Ein Vergleich verschiedener Modulationsverfahren wurde durchgeführt und die am besten geeigneten Verfahren für die Implementation in den Phasenbaustein ausgewählt. Eine Anforderung war, dass dieser Signale einer übergeordneten Regelung verarbeiten kann, welche für einen 2L-VSC berechnet wurden. Ein Überblick der Zwischenkreisbalancierungsverfahren zeigte, dass nahezu alle den Nachteil einer zusätzlich benötigten Strommessung haben. Die Untersuchung einer neuen an der Professur Leistungselektronik der TU Dresden entwickelten Methode ohne den Bedarf der Strommessung zeigte, dass diese anwendbar ist. Der Algorithmus wurde simuliert, implementiert und experimentell getestet und zeigte gute Resultate. Die Aufgabe eines komplett unabhängigen Kurzschlussschutzes war die schwierigste. Alle möglichen Fehler innerhalb eines Moduls wurden analysiert und kategorisiert. Einige Fehlertypen können innerhalb einer Phase behandelt werden. Entsprechende Algorithmen wurden entwickelt und getestet. Allerdings gibt es Fehlertypen, die nicht durch die Steuerung einer einzelnen Phase behandelt werden können. Eine schnelle Kommunikation zwischen den drei Phasen des Konverters wäre notwendig. Alternativ könnte eine übergeordnete Steuerung diese Fehler behandeln. Zum Schluss wurde ein Demonstrator des Phasenbausteins aufgebaut und experimentell untersucht. Einige Messergebnisse werden gezeigt, um die Funktion zu verifizieren.:1 Einleitung 1.1 Motivation 1.2 Zielstellung 1.3 Inhalt der Arbeit 2 Stromrichter für Windkraftanlagen 2.1 Stand der Technik 2.1.1 Zweipunktstromrichter mit Spannungszwischenkreis 2.1.2 Dreipunkt-Neutral-Point-Clamped-Stromrichter mit Spannungszwischenkreis 2.1.3 Kommerziell verfügbare Stromrichter für WKA 2.2 Vollumrichterlösung mit erhöhter Ausgangsspannung 2.2.1 Motivation und Anforderungen 2.2.2 Vereinfachter Vergleich von Zwei- und Dreipunktstromrichtern 2.3 Herausforderungen bei der Realisierung des 3L-NPC-VSC 3 Struktur und Funktion eines neuartigen 3L-NPC-Phasenbausteins 3.1 Struktur und Schnittstellen 3.1.1 Stand der Technik für 3L-NPC Phasenbausteine 3.1.2 Neuartiger 3L-NPC-VSC-Phasenbaustein 3.2 Realisierung 3.2.1 Anforderungen 3.2.2 Technische Realisierung 3.3 Experimentelle Verifikation 3.3.1 Versuchsstand 3.3.2 Messergebnisse 4 Modulation und Zwischenkreisbalancierung eines 3L-NPC-VSC 4.1 Modulationsarten im Überblick 4.1.1 Trägerbasierte Modulation für den 3L-NPC-VSC 4.2 Ausgewählte Modulation für den neuartigen Phasenbaustein 4.2.1 Zweipunktraumzeigermodulation in einem Trägerband 2L-SVM 4.2.2 Dreipunktraumzeigermodulation 3L-SVM 4.3 Stand der Technik bei Zwischenkreisbalancierungsverfahren 4.4 Die direkte Totzeitregelung zur Zwischenkreisbalancierung 4.4.1 Theoretische Grundlagen 4.4.2 Simulative Verifikation der direkten Totzeitregelung 4.4.3 Experimentelle Verifikation der DDTC 5 Kurzschlussschutz eines 3L-NPC-VSC-Phasenbausteins 5.1 Versuchsstand I5.2 Kurzschlussfehler einer 3L-NPC-VSC-Phase 5.2.1 Kategorisierung der Kurzschlüsse 5.2.2 Untersuchte Bauteilfehler innerhalb einer 3L-NPC-VSC-Phase 5.3 Kurzschlussbehandlungsmethoden 5.3.1 Stand der Technik 5.3.2 Schutzmaßnahmen für 3L-NPC-VSC 5.4 Analyse von Kurzschlüssen und Ableitung von Behandlungsmaßnahmen 5.4.1 Fehler eines äußeren IGBTs 5.4.2 Fehler eines inneren IGBTs 5.4.3 Fehler einer Clampdiode 5.5 Maßnahmen zur sicheren Behandlung von Kurzschlüssen in 3L-NPC-VSC 6 Zusammenfassun

How can we measure Email Overload?

In times of digital information and communication technologies the overload by emails becomes more and more relevant for many employees. To reduce or even avoid this overload, companies can implement specific countermeasures as soon as they recognize the overflow their employees’ experience. But if somebody is overloaded can not be answered directly by oneself; therefore it is necessary to use suitable constructs to measure email overload. This article includes a literature review to identify constructs to measure this phenomenon. From the field of information systems 55 highly ranked journals and conferences, furthermore 24 sources from the field of psychology were included. Finally, we could identify three different constructs by Dabbish and Kraut (2006), Hogan and Fisher (2006), and Sumecki, Chipulu and Ojiako (2011) to measure email overload. Beyond that, the article focuses on the description of the development of these instruments, discusses advantages and disadvantages, and gives an outlook what should be improved in these instruments in the future

Response of moist and dry processes in atmospheric blocking to climate change

Weather extremes are often associated with atmospheric blocking, but how the underlying physical processes leading to blocking respond to climate change is not yet fully understood. Here we track blocks as upper-level negative potential vorticity (PV) anomalies and apply a Lagrangian analysis to 100 years of present-day (∼2000) and future (∼2100, under the RCP8.5 scenario) climate simulations restarted from the Community Earth System Model–Large Ensemble Project runs (CESM-LENS) to identify different physical processes and quantify how their relative importance changes in a warmer and more humid climate. The trajectories reveal two contrasting airstreams that both contribute to the formation and maintenance of blocking: latent heating in strongly ascending airstreams (moist processes) and quasi-adiabatic flow near the tropopause with weak radiative cooling (dry processes). Both are reproduced remarkably well when compared against ERA-Interim reanalysis, and their relative importance varies regionally and seasonally. The response of blocks to climate change is complex and differs regionally, with a general increase in the importance of moist processes due to stronger latent heating (+1 K in the median over the Northern Hemisphere) and a larger fraction (+15%) of strongly heated warm conveyor belt air masses, most pronounced over the storm tracks. Future blocks become larger (+7%) and their negative PV anomaly slightly intensifies (+0.8%). Using a Theil–Sen regression model, we propose that the increase in size and intensity is related to the increase in latent heating, resulting in stronger cross-isentropic transport of air with low PV into the blocking anticyclones. Our findings provide evidence that moist processes become more important for the large-scale atmospheric circulation in the midlatitudes, with the potential for larger and more intense blocks

Very high stratospheric influence observed in the free troposphere over the northern Alps - just a local phenomenon?

The atmospheric composition is strongly influenced by a change in atmospheric dynamics, which is potentially related to climate change. A prominent example is the doubling of the stratospheric ozone component at the Zugspitze summit station (2962ma.s.l., Garmisch-Partenkirchen, Germany) between the mid-seventies and 2005, roughly from 11 to 23 ppb (43 %). Systematic efforts for identifying and quantifying this influence have been made since the late 1990s. Meanwhile, routine lidar measurements of ozone and water vapour carried out at Garmisch-Partenkirchen (German Alps) since 2007, combined with in situ and radiosonde data and trajectory calculations, have revealed that stratospheric intrusion layers are present on 84% of the yearly measurement days. At Alpine summit stations the frequency of intrusions exhibits a seasonal cycle with a pronounced summer minimum that is reproduced by the lidar measurements. The summer minimum disappears if one looks at the free troposphere as a whole. The mid- and uppertropospheric intrusion layers seem to be dominated by very long descent on up to hemispheric scale in an altitude range starting at about 4.5 km a.s.l. Without interfering air flows, these layers remain very dry, typically with RH ≤ 5% at the centre of the intrusion. Pronounced ozone maxima observed above Garmisch-Partenkirchen have been mostly related to a stratospheric origin rather than to long-range transport from remote boundary layers. Our findings and results for other latitudes seem to support the idea of a rather high contribution of ozone import from the stratosphere to tropospheric ozone

The unperceived boon and bane of Cloud Computing: End-user Computing vs. Integration

Cloud Computing is predicted to bring the next revolution in IT. Easy availability and the intuitive usability enable IT-professionals but also less IT-skilled people deploying IT-services. This encourages End-user Computing, where the end-user is able to solve business issues by designing the service as needed. But with end-users establishing such services, problems of integration occur due to the end-user’s lack of IT-knowledge and insufficient skills of conceptual IT-development. By conducting a case study following the design science approach, we pointed out that with establishing cloud services the degree of End-user Computing is increased and moreover influenced by the services applied. Furthermore we constrained that the independency from an IT-department ends up with the integration of end-user designed services in the existing IT-infrastructure. In order to solve this issue, we manually integrated IT-systems by the use of the Enterprise Architecture Integration approach