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  • Artikel  (270.967)
  • 2010-2014  (270.967)
  • Maschinenbau  (180.873)
  • Informatik  (90.586)
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  • 1
    Publikationsdatum: 2014-12-31
    Beschreibung: The paper deals with the investigation of some phenomena which are essential for dynamic interaction of a wheelset or bogie with the railways track. The track is modeled as discrete–continuous system composed of rails, fastening systems and sleepers interacting with ballast by means of viscous–elastic elements. Transient and stationary problems are investigated. The stationary periodic problems are connected with wave propagation in stopping bound, passing bound and mistuning. In this paper, a review of selected problems and exemplary results of simulation and experimental investigations is given supplemented by a few results of analysis and simulation.
    Print ISSN: 0939-1533
    Digitale ISSN: 1432-0681
    Thema: Maschinenbau
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2014-12-31
    Beschreibung: Background: Centralized silos of genomic data are architecturally easier to initially design, develop and deploy than distributed models. However, as interoperability pains in EHR/EMR, HIE and other collaboration-centric life sciences domains have taught us, the core challenge of networking genomics systems is not in the construction of individual silos, but the interoperability of those deployments in a manner embracing the heterogeneous needs, terms and infrastructure of collaborating parties. This article demonstrates the adaptation of BitTorrent to private collaboration networks in an authenticated, authorized and encrypted manner while retaining the same characteristics of standard BitTorrent. Results: The BitTorious portal was sucessfully used to manage many concurrent domestic Bittorrent clients across the United States: exchanging genomics data payloads in excess of 500GiB using the uTorrent client software on Linux, OSX and Windows platforms. Individual nodes were sporadically interrupted to verify the resilience of the system to outages of a single client node as well as recovery of nodes resuming operation on intermittent Internet connections. Conclusions: The authorization-based extension of Bittorrent and accompanying BitTorious reference tracker and user management web portal provide a free, standards-based, general purpose and extensible data distribution system for large ‘omics collaborations.
    Digitale ISSN: 1471-2105
    Thema: Biologie , Informatik
    Publiziert von BioMed Central
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    facet.materialart.
    Unbekannt
    Oxford University Press
    Publikationsdatum: 2014-12-31
    Beschreibung: High-performance computing (HPC) systems, including Clusters, Grids and the most recent Clouds, have emerged as attractive platforms to tackle various applications. One significant type of applications in the HPC systems is workflow computation, which has been applied in various scientific and engineering domains. The workflow computation frequently produces intermediate result files, which become garbage after being used and are usually cleaned up without making any contribution to future computation. In this paper, we argue that such garbage data could be useful in the future computation and should not be immediately cleaned up. This is because workflow computation usually contains multiple instances that may share some common data products produced in the past. This sharing scheme provides opportunities to reuse the historical data to speed-up subsequent computation and simplify re-computation due to faulty or crashed runs. To this end, we propose a novel approach, referred to as garbage data manager (GDM), for the workflow computation in HPC systems. The GDM organizes and manages the garbage data for batch schedulers to enhance the performance of subsequent computation. The essence of the GDM is to record the history of computation by constructing a dataflow graph on per instance (run) basis and set up inheritance relationships between the different instances of the same workflow, called run-tree , to achieve the data reuse. Our simulation results demonstrate that exploiting the garbage data is an effective way of improving the workflow computation.
    Print ISSN: 0010-4620
    Digitale ISSN: 1460-2067
    Thema: Informatik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    facet.materialart.
    Unbekannt
    Oxford University Press
    Publikationsdatum: 2014-12-31
    Beschreibung: The analysis of a queue that serves batches of customers with a novel service policy is presented in this paper, showing that a closed steady-state distribution of the number of customers in the queue can be derived for a very general setting of its parameters. Two output processes are flowing out of this queue depending on the fact that single customers are removed from the queue upon completion of a service, or bulks of customers of a fixed size are departing from the queue at the completion of the service's. Based on the expression of the steady-state distribution which assumes a Poisson arrival process, specific parameter configurations are identified that make the queue quasi-reversible, depending on the output process of interest. Since quasi-reversible queues are very important in the context of product form queueing networks, these results have relevant impacts on their own as well as when considered as the basis for possible computationally efficient approximations. Comparisons among the results obtained for different parameter settings are provided using both stochastic order arguments and numerical experiments. Future research directions are proposed considering also the many practical applications of this model ranging from flexible manufacturing, to logistics, to transportation systems.
    Print ISSN: 0010-4620
    Digitale ISSN: 1460-2067
    Thema: Informatik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2014-12-31
    Beschreibung: Without any doubt XML is currently a de facto standard for data representation. Its popularity is given by the fact that it is well-defined, easy-to-use, and, at the same time, sufficiently expressive. However, most of XML documents are still created without the respective description of their structure, i.e. an XML schema. Since the knowledge of XML schema is crucial for various data processing approaches as well as a standard optimization tool, approaches to (semi-)automatic inference of XML schema become an interesting research problem. Recently, there have been introduced several approaches that improve particular steps of the inference process. The problem is how to compare such approaches, how to find the optimal ones and how to join them to get the best possible result. In this paper, we introduce jInfer , a general framework for XML schema inference. It represents an easily extensible tool that enables one to implement, test and compare new modules of the inference process. Since the compulsory parts of the process, such as parsing of XML data, visualization of automata, transformation of automata to XML schema languages, etc. are implemented, the user can focus purely on the research and the improved aspect of the inference process. We describe not only the framework, but the area of schema inference in general, including related work and open problems.
    Print ISSN: 0010-4620
    Digitale ISSN: 1460-2067
    Thema: Informatik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2014-12-31
    Beschreibung: The popular Nelder and Mead (NM) algorithm has four parameters associated to the operations known as reflection, expansion, contraction and shrinkage. The authors set their values to 1, 2, 0.5 and 0.5, respectively, which have been universally used. Here, we propose to use NM to calibrate itself. A computational experiment is carried out and results show that the parameter values originally proposed by NM are better than those obtained with more sophisticated ways.
    Print ISSN: 0010-4620
    Digitale ISSN: 1460-2067
    Thema: Informatik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2014-12-31
    Beschreibung: Heat transfer and friction factor characteristics in a circular tube fitted with core rod at high temperature have been investigated experimentally. In the experiments, ambient air with Reynolds numbers in a range of 9,000–26,000 is passed through a circular tube with uniform wall temperature and convection and radiation heat transfer phenomena are studied. Experiments have been performed on the tube with core rod insert considering four values of uniform wall temperature. For each wall temperature considered, convection and radiation heat transfer coefficients have been determined. The experimental results show that at uniform wall temperature of 373, 473, 553 and 633 K the average share of the radiation heat transfer coefficient to the total heat transfer coefficient is 10.7, 14.6, 20.5 and 22.3 % respectively. In addition it was noted that for the mentioned temperatures, the heat transfer coefficient increased by 234, 275, 304 and 334 % respectively when using tube containing the core insert in comparison to the plain tube. It was also noted that increasing the wall temperature also resulted in increase of friction factor.
    Print ISSN: 0947-7411
    Digitale ISSN: 1432-1181
    Thema: Maschinenbau , Physik
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2014-12-31
    Beschreibung: The primary focus of this work was to determine the relationship between chemical composition and the Zener-Hollomon exponent q in the peak strain equation for hot working of C-Mn steels with the ultimate aim of improving the modeling of mean flow stresses for hot strip mills. Therefore, the hot deformation behavior of C-Mn steels was examined in which the C and Mn contents were increased systematically between the levels 0.035 up to 0.52%C and 0.22 to 1.58%Mn, respectively. In addition, data from other workers were also analyzed to complement the results from this investigation. As opposed to the observations from some other workers that the apparent activation energy for hot working Q HW appears to decrease with an increase in the carbon content, it was found that, despite a weak relationship, Q HW increases with an increase in carbon content i.e., from 300 to 355 kJ/mol as was also found by others. Consequently, the Zener-Hollomon exponent q in the peak strain equation for hot working and hence also the critical strain for dynamic recrystallisation, ε c  = 0.65 AD 0 m Z q , was found to decrease with an increase in carbon content as follows, q  = 0.21 − 14[%C] for C ≤ 0.8%C. The possible role played by manganese-carbon complexes in the austenite during hot working and the consequences of the variation in q for compact strip production rolling are discussed.
    Print ISSN: 1059-9495
    Digitale ISSN: 1544-1024
    Thema: Maschinenbau
    Publiziert von Springer im Namen von ASM International.
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2014-12-31
    Beschreibung: The effects of composition changes and heat treatment on the microstructure and mechanical properties of high-chromium white cast irons were studied in order to characterize possible improvements in product performance and machinability. Materials characterization was performed using nanoindentation, SEM, and EDS techniques. Present results show that changes in carbon and silicon contents as well as heat treatment strongly affect the mechanical properties and their variation in the material. In the as-cast condition, the sample with relatively lower carbon and silicon contents has an austenite-martensite matrix and is much harder than the sample with relatively higher carbon and silicon contents having more eutectic carbides in a bainite matrix. Annealing leads to softening of the materials relative to the as-cast condition, with the relatively higher carbon-silicon material being marginally harder due to the presence of more eutectic carbides. A similar trend is seen after the hardening treatment, and the presence of primary carbide can restrict the extent of hardening due to the loss of alloying elements from the matrix.
    Print ISSN: 1059-9495
    Digitale ISSN: 1544-1024
    Thema: Maschinenbau
    Publiziert von Springer im Namen von ASM International.
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2014-12-31
    Beschreibung: Thermal spraying of Cr 3 C 2 -NiCr composites generates varying degrees of carbide dissolution into the Ni binder. During high-temperature exposure, the carbide dissolution zones precipitate high concentrations of small carbides which develop into finely structured networks. This raises the possibility of producing unique tailored carbide composite structures through the generation of controlled carbide dissolution and appropriate heat treatment. The first step in this process is to produce a supersaturated Ni-Cr-C solid solution from which the carbide phase could be precipitated. In a previous work, a broad range of plasma parameters were trialed to assess their effect on the degree of carbide dissolution at a fixed spray distance of 100 mm. The current two-part work builds on the most promising plasma parameters from those trials. Part 2 of this article series investigated the effect of spray distance on the compositional development in Cr 3 C 2 -NiCr coatings during high-energy plasma spraying. The coating compositions were analyzed in detail and quantified through Rietveld fitting of the coating XRD patterns. Coating microstructural features were correlated with the observed variations in composition. The effect of the spray parameters and spray distance on the equilibrium coating compositions is discussed.
    Print ISSN: 1059-9630
    Digitale ISSN: 1544-1016
    Thema: Maschinenbau
    Publiziert von Springer im Namen von ASM International.
    Standort Signatur Erwartet Verfügbarkeit
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