77,901 research outputs found

    PoN-S : a systematic approach for applying the Physics of Notation (PoN)

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    Visual Modeling Languages (VMLs) are important instruments of communication between modelers and stakeholders. Thus, it is important to provide guidelines for designing VMLs. The most widespread approach for analyzing and designing concrete syntaxes for VMLs is the so-called Physics of Notation (PoN). PoN has been successfully applied in the analysis of several VMLs. However, despite its popularity, the application of PoN principles for designing VMLs has been limited. This paper presents a systematic approach for applying PoN in the design of the concrete syntax of VMLs. We propose here a design process establishing activities to be performed, their connection to PoN principles, as well as criteria for grouping PoN principles that guide this process. Moreover, we present a case study in which a visual notation for representing Ontology Pattern Languages is designed

    The Case for Combining a Large Low-Band Very High Frequency Transmitter With Multiple Receiving Arrays for Geospace Research: A Geospace Radar

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    We argue that combining a high‐power, large‐aperture radar transmitter with several large‐aperture receiving arrays to make a geospace radar—a radar capable of probing near‐Earth space from the upper troposphere through to the solar corona—would transform geospace research. We review the emergence of incoherent scatter radar in the 1960s as an agent that unified early, pioneering research in geospace in a common theoretical, experimental, and instrumental framework, and we suggest that a geospace radar would have a similar effect on future developments in space weather research. We then discuss recent developments in radio‐array technology that could be exploited in the development of a geospace radar with new or substantially improved capabilities compared to the radars in use presently. A number of applications for a geospace radar with the new and improved capabilities are reviewed including studies of meteor echoes, mesospheric and stratospheric turbulence, ionospheric flows, plasmaspheric and ionospheric irregularities, and reflection from the solar corona and coronal mass ejections. We conclude with a summary of technical requirements

    Edge Elimination in TSP Instances

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    The Traveling Salesman Problem is one of the best studied NP-hard problems in combinatorial optimization. Powerful methods have been developed over the last 60 years to find optimum solutions to large TSP instances. The largest TSP instance so far that has been solved optimally has 85,900 vertices. Its solution required more than 136 years of total CPU time using the branch-and-cut based Concorde TSP code [1]. In this paper we present graph theoretic results that allow to prove that some edges of a TSP instance cannot occur in any optimum TSP tour. Based on these results we propose a combinatorial algorithm to identify such edges. The runtime of the main part of our algorithm is O(n2logn)O(n^2 \log n) for an n-vertex TSP instance. By combining our approach with the Concorde TSP solver we are able to solve a large TSPLIB instance more than 11 times faster than Concorde alone

    Impact of microphysics schemes in the simulation of cyclone hudhud using WRF-ARW model

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    A Very Severe Cyclonic Strom (VSCS) "Hudhud" crossed Andhra coast near Visakhapatnam on 12th October 2014 and caused significant damage to property due to both wind and surge. In the present study, an attempt is made to simulate and test the capability of the state of art Advanced Research Weather Research and Forecasting (WRF-ARW) model in capturing the wind intensity and track of cyclone accurately. The simulation has been carried out using three domains with a horizontal resolution of 27 km for domain 1, 9 km for domain 2 and 3 km for domain 3. Multiple simulations using initial conditions (NCEP FNL) at an interval of 6 hours, same cumulus parameterization and time integration schemes but with different microphysics schemes are carried out. The main source of energy for tropical cyclone is the latent hear release (convective heating) in clouds, which depend on microphysical processes and the released dynamical properties. The objective of the present study is to find out the best microphysics for accurate simulation of intensity and track of tropical cyclone at high model domain resolution towards storm surge studies. The best performance was found for the model integrated for 48 hours starting from 10th October 2014 to 12th October 2014. Simulated features include (track, maximum sustained wind, sea level pressure and rainfall) were compared with IMD best track data and it was observed that simulations with WRF LIN microphysics scheme compare well with observations. Other synoptic features of rainfall was also simulated and discussed in relation to model performance. Overall this study gives emphasis on the studies towards sensitivity analysis of microphysics parameterization using WRF simulations at high model grid resolution (3 km) to imply towards storm surge applications in Bay of Bengal

    Shearlets and Optimally Sparse Approximations

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    Multivariate functions are typically governed by anisotropic features such as edges in images or shock fronts in solutions of transport-dominated equations. One major goal both for the purpose of compression as well as for an efficient analysis is the provision of optimally sparse approximations of such functions. Recently, cartoon-like images were introduced in 2D and 3D as a suitable model class, and approximation properties were measured by considering the decay rate of the L2L^2 error of the best NN-term approximation. Shearlet systems are to date the only representation system, which provide optimally sparse approximations of this model class in 2D as well as 3D. Even more, in contrast to all other directional representation systems, a theory for compactly supported shearlet frames was derived which moreover also satisfy this optimality benchmark. This chapter shall serve as an introduction to and a survey about sparse approximations of cartoon-like images by band-limited and also compactly supported shearlet frames as well as a reference for the state-of-the-art of this research field.Comment: in "Shearlets: Multiscale Analysis for Multivariate Data", Birkh\"auser-Springe

    Dust penetrated morphology in the high redshift Universe

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    Images from the Hubble Deep Field (HDF) North and South show a large percentage of dusty, high redshift galaxies whose appearance falls outside traditional classification systems. The nature of these objects is not yet fully understood. Since the HDF preferentially samples restframe UV light, HDF morphologies are not dust or `mask' penetrated. The appearance of high redshift galaxies at near-infrared restframes remains a challenge for the New Millennium. The Next Generation Space Telescope (NGST) could routinely provide us with such images. In this contribution, we quantitatively determine the dust-penetrated structures of high redshift galaxies such as NGC 922 in their near-infrared restframes. We show that such optically peculiar objects may readily be classified using the dust penetrated z ~ 0 templates of Block and Puerari (1999) and Buta and Block (2001).Comment: 4 pages, 2 figures. Presented at the conference "The Link between Stars and Cosmology", 26-30 March, 2001, Puerto Vallarta, Mexico. To be published by Kluwer, eds. M. Chavez, A. Bressan, A. Buzzoni, and D. Mayya. High-resolution version of Figure 2 can be found at http://www.inaoep.mx/~puerari/conf_puertovallart

    Graph-Embedding Empowered Entity Retrieval

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    In this research, we improve upon the current state of the art in entity retrieval by re-ranking the result list using graph embeddings. The paper shows that graph embeddings are useful for entity-oriented search tasks. We demonstrate empirically that encoding information from the knowledge graph into (graph) embeddings contributes to a higher increase in effectiveness of entity retrieval results than using plain word embeddings. We analyze the impact of the accuracy of the entity linker on the overall retrieval effectiveness. Our analysis further deploys the cluster hypothesis to explain the observed advantages of graph embeddings over the more widely used word embeddings, for user tasks involving ranking entities
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