1,344 research outputs found

    Microwave burst with fine spectral structures in a solar flare on 2011 August 9

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    On August 9, 2011, there was an X6.9 flare event occurred near the west limb of solar disk. From the observation obtained by the spectrometer of the Chinese Solar Broadband Radio Spectrometer in Huairou (SBRS/Huairou) around the flare, we find that this powerful flare has only a short-duration microwave burst of about only 5 minutes, and during the short-duration microwave burst, there are several kinds of fine structures on the spectrogram. These fine structures include very short-period pulsations, millisecond spike bursts, and type III bursts. The most interesting is that almost all of the pulses of very short-period pulsation (VSP) are structured by clusters of millisecond timescales of spike bursts or type III bursts. And there exists three different kinds of frequency drift rates in the VSP: the frequency drift rates with absolute value of about 55 - 130 MHz s^{-1} in the pulse groups, the frequency drift rates with absolute value of about 2.91 - 16.9 GHz s^{-1} on each individual pulse, and the frequency drift rates with absolute value of about 15 - 25 GHz s1^{-1}) at each individual spike burst or type III burst.Comment: 5 pages, 3 figure

    A framework for integrating syntax, semantics and pragmatics for computer-aided professional practice: With application of costing in construction industry

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    Producing a bill of quantity is a knowledge-based, dynamic and collaborative process, and evolves with variances and current evidence. However, within the context of information system practice in BIM, knowledge of cost estimation has not been represented, nor has it been integrated into the processes based on BIM. This paper intends to establish an innovative means of taking data from the BIM linked to a project, and using it to create the necessary items for a bill of quantity that will enable cost estimation to be undertaken for the project. Our framework is founded upon the belief that three components are necessary to gain a full awareness of the domain which is being computerised; the information type which is to be assessed for compatibility (syntax), the definition for the pricing domain (semantics), and the precise implementation environment for the standards being taken into account (pragmatics). In order to achieve this, a prototype is created that allows a cost item for the bill of quantity to be spontaneously generated, by means of the semantic web ontology and a forward chain algorithm. Within this paper, ‘cost items’ signify the elements included in a bill of quantity, including details of their description, quantity and price. As a means of authenticating the process being developed, the authors of this work effectively implemented it in the production of cost items. In addition, the items created were contrasted with those produced by specialists. For this reason, this innovative framework introduces the possibility of a new means of applying semantic web ontology and forward chain algorithm to construction professional practice resulting in automatic cost estimation. These key outcomes demonstrate that, decoupling the professional practice into three key components of syntax, semantics and pragmatics can provide tangible benefits to domain use

    Towards a Quality Reference Framework for MOOCs

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    This paper aims to address the quality issues of open online education and learning with a focus on MOOCs. Specifically, our research goal is to develop a Quality Reference Framework (QRF) with quality indicators and tools in close collaboration with all interested stakeholders worldwide. Based on a rigorous literature review and analysis of existing quality approaches and quality indicators for MOOCs, the Global MOOC Quality Survey was designed targeting at three core interest groups: MOOC learners, MOOC designers and MOOC facilitators. A total of n=267 took part in the survey. The survey results were complemented with 45 semi-structured interviews with MOOC designers, facilitators and providers. This mixed method research was selected to provide a more coherent picture and analysis of the quality issues of MOOCs by investigating them from diverse and different perspectives. This paper presents first results from the survey and semi-structured interviews, the first QRF draft and the feedback gained from workshops at international conferences

    Evolving rules for document classification

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    We describe a novel method for using Genetic Programming to create compact classification rules based on combinations of N-Grams (character strings). Genetic programs acquire fitness by producing rules that are effective classifiers in terms of precision and recall when evaluated against a set of training documents. We describe a set of functions and terminals and provide results from a classification task using the Reuters 21578 dataset. We also suggest that because the induced rules are meaningful to a human analyst they may have a number of other uses beyond classification and provide a basis for text mining applications

    Exact algorithms to minimize interference in wireless sensor networks

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    AbstractFinding a low-interference connected topology is a fundamental problem in wireless sensor networks (WSNs). The problem of reducing interference through adjusting the nodes’ transmission radii in a connected network is one of the most well-known open algorithmic problems in wireless sensor network optimization. In this paper, we study minimization of the average interference and the maximum interference for the highway model, where all the nodes are arbitrarily distributed on a line. First, we prove that there is always an optimal topology with minimum interference that is planar. Then, two exact algorithms are proposed. The first one is an exact algorithm to minimize the average interference in polynomial time, O(n3Δ), where n is the number of nodes and Δ is the maximum node degree. The second one is an exact algorithm to minimize the maximum interference in sub-exponential time, O(n3ΔO(k)), where k=O(Δ) is the minimum maximum interference. All the optimal topologies constructed are planar

    Can patterns of everyday consumption indicate lifestyles? A secondary analysis of expenditures for fast moving goods and their social contexts

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    Ausgangspunkt der vorliegenden Studie bildet die Frage, ob sich Einkaufsformen beim täglichen Verbrauch als grundlegende Indikatoren von Lebensstilen erweisen. Datengrundlage bildet eine Sekundäranalyse von Panel-Daten zum Konsum schnelllebiger Waren, die vom weltweiten Marktforschungsunternehmen GfK im Jahr 1995 erhoben worden sind. Es wird zunächst eine Reihe von Hypothesen aufgestellt und die zugrunde gelegten Daten und die Stichprobe erläutert. Im Hauptteil der Studie werden 15 vollständige Cluster des Kaufverhaltens von Waren aus den Bereichen Nahrungsmittel, Getränke und Hygiene-Artikel untersucht und mit ausgewählten sozialen Indikatoren, wie z.B. sozialer Status, Mentalität und Umweltbewusstsein in Beziehung gesetzt. Die Ergebnisse zeigen, dass selbst der Kauf von schnelllebigen Konsumgütern in breitere Lebensstile eingebettet ist und auch im Zeitverlauf relativ konstant bleibt. (ICI

    Continuous-variable quantum teleportation of entanglement

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    Entangled coherent states can be used to determine the entanglement fidelity for a device that is designed to teleport coherent states. This entanglement fidelity is universal, in that the calculation is independent of the use of entangled coherent states and applies generally to the teleportation of entanglement using coherent states. The average fidelity is shown to be a poor indicator of the capability of teleporting entanglement; i.e., very high average fidelity for the quantum teleportation apparatus can still result in low entanglement fidelity for one mode of the two-mode entangled coherent state.Comment: 5 pages, 1 figure, published versio
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