59 research outputs found

    SatellitengestĂŒtzte DatenĂŒbertragung

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    Diese Diplomarbeit beschreibt die Möglichkeiten des satellitengestĂŒtzten Datentransfers und richtet sich in erster Linie an Marketing- und Trademanager grĂ¶ĂŸerer Handelsketten und Konzerne, sowie Multimedia-Agenturen, die auf der Suche nach technischen Neuerungen bei der Nutzung interaktiver Verkaufsterminals sind. Das Ziel ist, ĂŒber die Möglichkeiten und Vorteile der SatellitenĂŒbertragung umfassend zu informieren, Vorteile und Einsatzmöglichkeiten aufzuzeigen, den wirtschaftlichen Nutzen zu erlĂ€utern, sowie eventuell entstehende Probleme anzusprechen und Lösungsmöglichkeiten anzubieten. DarĂŒber hinaus werden die wichtigsten technischen Grundbegriffe geklĂ€rt, sowie aktuelle Standards angesprochen. Die Diplomarbeit enthĂ€lt des weiteren die an einem Fallbeispiel genau erlĂ€uterte Phasen der Entstehung und Implementierung eines satellitengestĂŒtzten POS-Netzes, sowie eine detaillierte Kostenauflistung

    Observational Requirements for Lyman-alpha Forest Tomographic Mapping of Large-Scale Structure at z ~ 2

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    The z > 2 Lyman-alpha (Lya) forest traces the underlying dark-matter distribution on large scales and, given sufficient sightlines, can be used to create 3D maps of large-scale structure. We examine the observational requirements to construct such maps and estimate the signal-to-noise as a function of exposure time and sightline density. Sightline densities at z = 2.25 are n_los = [360, 1200,3300] deg^{-2} at limiting magnitudes of g =[24.0, 24.5,25.0], resulting in transverse sightline separations of d_perp = [3.6, 1.9, 1.2] h^{-1} Mpc, which roughly sets the reconstruction scale. We simulate these reconstructions using mock spectra with realistic noise properties, and find that spectra with S/N = 4 per angstrom can be used to generate maps that clearly trace the underlying dark-matter at overdensities of rho/ ~ 1. For the VLT/VIMOS spectrograph, exposure times t_exp = [4, 6, 10] hrs are sufficient for maps with spatial resolution epsilon_3d = [5.0, 3.2, 2.3] h^{-1} Mpc. Assuming ~ 250 h^{-1} Mpc is probed along the line-of-sight, 1 deg^2 of survey area would cover a comoving volume of ~ 10^6 h^{-3} Mpc^3 at =2.3, enabling efficient mapping of large volumes with 8-10m telescopes. These maps could be used to study galaxy environments, detect proto-clusters, and study the topology of large-scale structure at high-z.Comment: 18 pages, 10 figures. Accepted by Ap

    Proceedings of the 5th bwHPC Symposium

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    In modern science, the demand for more powerful and integrated research infrastructures is growing constantly to address computational challenges in data analysis, modeling and simulation. The bwHPC initiative, founded by the Ministry of Science, Research and the Arts and the universities in Baden-WĂŒrttemberg, is a state-wide federated approach aimed at assisting scientists with mastering these challenges. At the 5th bwHPC Symposium in September 2018, scientific users, technical operators and government representatives came together for two days at the University of Freiburg. The symposium provided an opportunity to present scientific results that were obtained with the help of bwHPC resources. Additionally, the symposium served as a platform for discussing and exchanging ideas concerning the use of these large scientific infrastructures as well as its further development

    5. und 6. Tagung GMLÂČ 2007 und GMLÂČ 2008 ; 19. - 21. MĂ€rz 2007 / 13. - 14. MĂ€rz 2008 an der Technischen UniversitĂ€t Berlin und an der Freien UniversitĂ€t Berlin

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    Dem Lernen und Lehren mit Neuen Medien werden in Zeiten der Informationsgesellschaft oft sagenhafte Eigenschaften zugeschrieben: es sei anschaulicher, attraktiver, motivierender, effizienter, kostengĂŒnstiger, gehe besser auf den Lernenden ein, steigere den Lernerfolg, orientiere sich mehr an den kognitiven Strukturen von Lernenden etc.. Damit wenigstens einige der genannten Vorteile wirksam werden, sind geeignete didaktische und methodische Modelle und Konzepte unverzichtbar. Hinzu kommen detaillierte Kenntnisse in der Gestaltung von LernoberflĂ€chen, der technischen Realisierung von Lerninhalten, dem Aufbau lernförderlicher Strukturen und Betreuungskonzepte und dem Betrieb von teilweise virtuellen UniversitĂ€ten. Inwieweit gesteckte Ziele erreicht wurden, ist anhand von Evaluationsmaßnahmen zu ermitteln. SĂ€mtliche Aspekte mĂŒssen bereits in die Planung entsprechender Angebote einbezogen werden. Die Tagungsreihe widmet sich ausgewĂ€hlten Fragestellungen dieses Themenkomplexes, die durch VortrĂ€ge ausgewiesener Experten, durch eingereichte BeitrĂ€ge und durch Diskussionen in Arbeitsgruppen/Tutorials intensiv behandelt werden. Der Schwerpunkt liegt dabei auf den didaktischen und methodischen Konzepten, die im Rahmen multimedialer Lehre zum Einsatz kommen. Zur PrĂ€sentation von Beispielszenarien, Projektergebnissen, Best- Practice sowie zum Erfahrungsaustausch sind ebenfalls stets ausreichend FreirĂ€ume eingeplant. Als Zielgruppe sehen wir u.a. Interessentinnen und Interessenten, die – vor allem im Raum Berlin/Brandenburg – an Entwicklung und Einsatz von multimedialen Lehrangeboten arbeiten. Besonders angesprochen sind Mitarbeiter und Mitarbeiterinnen in den laufenden BMBF-Förderprojekten im Programm „Neue Medien in der Bildung“ und in Bildungsinitiativen und -projekten zur Gestaltung der Informationsgesellschaft. Eingeladene HauptvortrĂ€ge und eingereichte BeitrĂ€ge haben die GMLÂČ 2007 und die GMLÂČ 2008 neben einem Tutorial zu Serious Learning und der Verabschiedung von Thesen zu den Grundfragen multimedialer Lehre und Lernens besonders geprĂ€gt. Es wurden VortrĂ€ge zur PrĂ€sentation angenommen aus Themenbereichen wie Lernszenarien, Online-Learning, Methodik und Didaktik von Lernmodulen, Verteilte Kollaboration, Folie und Blended Learning, hybride Lernumgebungen, Mobile GerĂ€te fĂŒr Blended Learning, Instruktionsdesign, didaktische Modellierungswerkzeuge, Lernplattformen, Knowledge Sharing, Medien in der Softwareausbildung, E-Learning global, MedienverbĂŒnde, E-Learning Produktionsprozess, Online-Betreuung, Kommunikation und Neue Medien im Mathematikunterricht. Ein Posterprogramm begleitete die Tagungen. Die Reihenfolge dieses Doppelbandes ist inhaltlich geordnet, in Reihenfolge Konzepten des eLearning ĂŒber Studien/Projekte zu Werkzeugen

    Library buildings around the world

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    "Library Buildings around the World" is a survey based on researches of several years. The objective was to gather library buildings on an international level starting with 1990

    Integration und Konnexion : Tagungsband zur 26. AKWI-Jahrestagung vom 15. bis 18.09.2013 an der Technischen Hochschule Mittelhessen

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    Das aufgerufene Thema „Herausforderungen an die Wirtschaftsinformatik: Integration und Konnexion“ provozierte BeitrĂ€ge, die thematisch ein sehr breites Spektrum abdecken. Neben theoretischen Betrachtungen und Definitionen des sicher noch nicht final geprĂ€gten Begriffs der Konnexion gab es auch sehr praktische BeitrĂ€ge wie die Darstellung von konkreten prototypischen Entwicklungsvorhaben. Auch das ist ein Indiz fĂŒr die lebendige Landschaft der Wirtschaftsinformatik an den deutschsprachigen Hochschulen fĂŒr Angewandte Wissenschaften

    Model-Based Design, Analysis, and Implementations for Power and Energy-Efficient Computing Systems

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    Modern computing systems are becoming increasingly complex. On one end of the spectrum, personal computers now commonly support multiple processing cores, and, on the other end, Internet services routinely employ thousands of servers in distributed locations to provide the desired service to its users. In such complex systems, concerns about energy usage and power consumption are increasingly important. Moreover, growing awareness of environmental issues has added to the overall complexity by introducing new variables to the problem. In this regard, the ability to abstractly focus on the relevant details allows model-based design to help significantly in the analysis and solution of such problems. In this dissertation, we explore and analyze model-based design for energy and power considerations in computing systems. Although the presented techniques are more generally applicable, we focus their application on large-scale Internet services operating in U.S. electricity markets. Internet services are becoming increasingly popular in the ICT ecosystem of today. The physical infrastructure to support such services is commonly based on a group of cooperative data centers (DCs) operating in tandem. These DCs are geographically distributed to provide security and timing guarantees for their customers. To provide services to millions of customers, DCs employ hundreds of thousands of servers. These servers consume a large amount of energy that is traditionally produced by burning coal and employing other environmentally hazardous methods, such as nuclear and gas power generation plants. This large energy consumption results in significant and fast-growing financial and environmental costs. Consequently, for protection of local and global environments, governing bodies around the globe have begun to introduce legislation to encourage energy consumers, especially corporate entities, to increase the share of renewable energy (green energy) in their total energy consumption. However, in U.S. electricity markets, green energy is usually more expensive than energy generated from traditional sources like coal or petroleum. We model the overall problem in three sub-areas and explore different approaches aimed at reducing the environmental foot print and operating costs of multi-site Internet services, while honoring the Quality of Service (QoS) constraints as contracted in service level agreements (SLAs). Firstly, we model the load distribution among member DCs of a multi-site Internet service. The use of green energy is optimized considering different factors such as (a) geographically and temporally variable electricity prices, (b) the multitude of available energy sources to choose from at each DC, (c) the necessity to support more than one SLA, and, (d) the requirements to offer more than one service at each DC. Various approaches are presented for solving this problem and extensive simulations using Google’s setup in North America are used to evaluate the presented approaches. Secondly, we explore the area of shaving the peaks in the energy demand of large electricity consumers, such as DCs by using a battery-based energy storage system. Electrical demand of DCs is typically peaky based on the usage cycle of their customers. Resultant peaks in the electrical demand require development and maintenance of a costlier energy delivery mechanism, and are often met using expensive gas or diesel generators which often have a higher environmental impact. To shave the peak power demand, a battery can be used which is charged during low load and is discharged during the peak loads. Since the batteries are costly, we present a scheme to estimate the size of battery required for any variable electrical load. The electrical load is modeled using the concept of arrival curves from Network Calculus. Our analysis mechanism can help determine the appropriate battery size for a given load arrival curve to reduce the peak. Thirdly, we present techniques to employ intra-DC scheduling to regulate the peak power usage of each DC. The model we develop is equally applicable to an individual server with multi-/many-core chips as well as a complete DC with an intermix of homogeneous and heterogeneous servers. We evaluate these approaches on single-core and multi-core chip processors and present the results. Overall, our work demonstrates the value of model-based design for intelligent load distribution across DCs, storage integration, and per DC optimizations for efficient energy management to reduce operating costs and environmental footprint for multi-site Internet services

    Structural studies of eukaryotic ribosome biogenesis and the sec and Bcs1 protein translocation systems

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    Three publications of this cumulative dissertation use cryo-electron microscopy (cryo-EM) to dissect the assembly pathway of the eukaryotic large ribosomal subunit (LSU). This pathway commences with freshly transcribed and initially unfolded rRNA in the nucleolus, which folds and incorporates ribosomal proteins while traveling to the cytoplasm, ultimately culminating in the mature LSU. During this highly complex pathway, the yeast cell must assemble four rRNAs and 79 ribosomal proteins with the help of over 200 assembly factors (AFs). Using cryo-EM, structures of nucleo\-plasmic and cytoplasmic assembly intermediates of the LSU could be solved in recent years, thus shedding light on the later stages of LSU formation. Early assembly steps remain enigmatic, as nucleolar LSU assembly intermediates have been biochemically but not structurally characterized. Taken together, we solved the structure of seven nucleolar or early nucleoplasmic intermediates at resolutions ranging from 3.3 to 4.5 Å, showing a linear assembly sequence. The first five structures show how the rRNA of the LSU is incorporated stepwise, in a non-transcriptional sequence, first forming the solvent exposed back side, and later the peptide exit tunnel and parts of the intersubunit surface (ISS). At the late nucleolar stage, the L1-stalk rRNA of domain V blocks the site of central protuberance (CP) assembly and is stabilized in a premature conformation by a range of AFs associated with the meandering, long N-terminal tail of Erb1. Two further structures show progression from this stage after release of the Erb1-Ytm1 complex by the Rea1 remodeling machinery. These intermediates, purified via Nop53, show dissociation of many early AFs from the premature ISS and destabilization of the L1-stalk. After subsequent release of the Spb1 methyltransferase, the L1-stalk rRNA can be accommodated in its mature conformation. This allows the premature CP to form, leading to a previously characterized nucleoplasmic intermediate, with a formed but premature CP. This particle is the substrate for the second Rea1 mediated structural remodeling, an intermediate of which we resolved to molecular resolution revealing Ipi1 as a central integrator for the Rix1-Ipi1-Ipi3 complex on this pre-60S particle. The binding of the Rix1-Rea1 remodeling machinery at this nucleoplasmic stage progresses maturation by inducing a 180∘^{\circ} rotation of the 5S ribonucleoprotein particle (5S RNP) and CP. Using a combination of yeast genetics and cryo-EM we investigated the function of the AF Cgr1 in this maturation step. We showed that Cgr1 is required for CP rotation to take place, likely by stabilizing the rotated conformation. The Cgr1 function can be bypassed by introducing suppressor mutations in Rpf2 and Rrs1, two factors stabilizing the CP prior to rotation. Apart from ribosome biogenesis, two additional publications of this dissertation address protein translocation machinery, required for transport of proteins across or into membranes. The Sec translocon allows co- and posttranslational translocation of mostly unfolded substrates across the bacterial plasma and the eukaryotic endoplasmic reticulum (ER) membrane. We solved the structure of a stalled 70S ribosome-nascent chain complex (RNC) bound to the SecYEG translocon in a native like environment provided by a large lipid nanodisc. The structure shows all three subunits of the bacterial SecYEG complex and displays the lateral gate at a defined, early stage of opening or unzipping on the cytoplasmic side upon insertion of the signal anchor domain of the nascent chain. Specific pathways, such as the assembly of the mitochondrial bc1 respiratory chain complex, require folding of proteins in one compartment before translocation across a membrane to allow the protein to be active in another compartment. The bc1-complex component Rip1 folds in the mitochondrial matrix and assembles a 2Fe-2S cluster before being translocated across the inner mitochondrial membrane (IM) by the AAA-protein Bcs1. We solved the structure of Bcs1 in an ADP-bound state and two apo states, displaying a heptameric ring of Bcs1 protomers. Bcs1 forms two large aqueous vestibules separated by a seal forming middle domain. One vestibule is accessible from the matrix side and one lies within the inner mitochondrial membrane. The architecture and structural dynamics between the three states suggest an airlock like mechanism, allowing transport of folded Rip1 while maintaining the permeability barrier of the membrane
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