6,463 research outputs found

    Allowing Overlapping Boundaries in Source Code using a Search Based Approach to Concept Binding

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    One approach to supporting program comprehension involves binding concepts to source code. Previously proposed approaches to concept binding have enforced nonoverlapping boundaries. However, real-world programs may contain overlapping concepts. This paper presents techniques to allow boundary overlap in the binding of concepts to source code. In order to allow boundaries to overlap, the concept binding problem is reformulated as a search problem. It is shown that the search space of overlapping concept bindings is exponentially large, indicating the suitability of sampling-based search algorithms. Hill climbing and genetic algorithms are introduced for sampling the space. The paper reports on experiments that apply these algorithms to 21 COBOL II programs taken from the commercial financial services sector. The results show that the genetic algorithm produces significantly better solutions than both the hill climber and random search

    A theoretical and empirical study of EFSM dependence.

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    Dependence analysis underpins many activities in software maintenance such as comprehension and impact analysis. As a result, dependence has been studied widely for programming languages, notably through work on program slicing. However, there is comparatively little work on dependence analysis at the model level and hitherto, no empirical studies. We introduce a slicing tool for extended finite state machines (EFSMs) and use the tool to gather empirical results on several forms of dependence found in ten EFSMs, including well-known benchmarks in addition to real-world EFSM models. We investigate the statistical properties of dependence using statistical tests for correlation and formalize and prove four of the empirical findings arising from our empirical study. The paper thus provides the maintainer with both empirical data and foundational theoretical results concerning dependence in EFSM models

    New evidence for lack of CMB power on large scales

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    A digitalized temperature map is recovered from the first light sky survey image published by the Planck team, from which an angular power spectrum is derived. The amplitudes of the low multipoles measured from the preliminary Planck power spectrum are significantly lower than that reported by the WMAP team. Possible systematical effects are far from enough to explain the observed low-l differences.Comment: 9 pages, 3 figure

    Anomalous anisotropic cross-correlations between WMAP CMB maps and SDSS galaxy distribution and implications on the dark flow scenario

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    We search for the dark flow induced diffuse kinetic Sunyaev Zel'dovich (kSZ) effect through CMB-galaxy cross correlation. Such angular correlation is anisotropic, with a unique cos(thetaDF)cos(theta_DF) angular dependence and hence can be distinguished from other components. Here, thetaDFtheta_DF is the angle between the opposite dark flow direction and the direction of the sky where the correlation is measured. We analyze the KIAS-VAGC galaxy catalog of SDSS-DR7 and the WMAP seven-year temperature maps, applying an unbiased optimal weighting scheme to eliminate any statistically isotropic components and to enhance the dark flow detection signal. Non-zero weighted cross correlations are detected at 3.5 sigma for the redshift bin z<0.1 and at 3 sigma for the bin 0.1<z<0.2, implying the existence of statistically anisotropic components in CMB. However, further analysis does not support the dark flow explanation. The observed directional dependence deviates from the āˆcos(thetaDF)\propto cos(theta_DF) relation expected, and hence can not be explained by the presence of a single dark flow, and if the observed cross correlation is generated by the dark flow induced kSZ effect, the velocity would be too high (> 6000 km/s). We report this work as the first attempt to search for dark flow through weighted CMB-galaxy cross correlation and to draw the attention on the sources of the detected anomalous CMB-galaxy cross correlation.Comment: 8 pages, 8 figures, ApJ accepte

    Is thermodynamics of the universe bounded by the event horizon a Bekenstein system?

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    In this brief communication, we have studied the validity of the first law of thermodynamics for the universe bounded by event horizon with two examples. The key point is the appropriate choice of the temperature on the event horizon. Finally, we have concluded that universe bounded by the event horizon may be a Bekenstein system and the Einstein's equations and the first law of thermodynamics on the event horizons are equivalent.Comment: 4 pages; accepted for publication in Phys. Lett.

    Dynamical Capture Binary Neutron Star Mergers

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    We study dynamical capture binary neutron star mergers as may arise in dense stellar regions such as globular clusters. Using general-relativistic hydrodynamics, we find that these mergers can result in the prompt collapse to a black hole or in the formation of a hypermassive neutron star, depending not only on the neutron star equation of state but also on impact parameter. We also find that these mergers can produce accretion disks of up to a tenth of a solar mass and unbound ejected material of up to a few percent of a solar mass. We comment on the gravitational radiation and electromagnetic transients that these sources may produce.Comment: 6 pages, 4 figures; revised to match published versio

    Pseudo-Dipole Signal Removal from WMAP Data

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    It is discovered in our previous work that different observational systematics, e.g., errors of antenna pointing directions, asynchronous between the attitude and science data, can generate pseudo-dipole signal in full-sky maps of the cosmic microwave background (CMB) anisotropy published by The Wilkinson Microwave Anisotropy Probe (WMAP) team. Now the antenna sidelobe response to the Doppler signal is found to be able to produce similar effect as well. In this work, independent to the sources, we uniformly model the pseudo-dipole signal and remove it from published WMAP7 CMB maps by model fitting. The result demonstrates that most of the released WMAP CMB quadrupole is artificial.Comment: V3: using WMAP7 dat

    Why the braking indices of young pulsars are less than 3?

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    In this letter we discuss two possible reasons which cause the observed braking indices n of young radio pulsars to be smaller than 3: (a) the evolving spin-down model of the magnetic field component BāŠ„B_{\perp} increases with time; (b) the extrinsic braking torque model in which the tidal torques exerted on the pulsar by the fallback disk, and carries away the spin angular momentum from the pulsar. Based on some simple assumptions, we derive the expression of the braking indices, and calculate the spin-down evolutionary tracks of pulsars for different input parameters.Comment: 4 pages, 3 figures, accepted for publication in A&A Letter

    Three-dimensional Geological Modeling Methods and Applications -A

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    Abstract. The ideas and methods of modeling are: According to each well in the simulation area geology, well logging data, combined with deposit information to geostatistics theory, establish the spatial distribution of the various geological parameters model, using interpolation techniques to predict the geological parameters for each grid block, three-dimensional geological model should include quantitative structural model, sand skeleton model, physical model and the gas-water distribution model. Currently, the three-dimensional geological modeling software more sophisticated, this study selected the Schlumberger Petrel software as a tool for research. Geological modeling generally follow the step point ā†’ surface ā†’ body. That modeling data preparation, structure modeling, and reservoir modeling with parametric modeling. Establish A Geological Repository There are 187 drilling modeling work area, an area 61.7km2, modeling requires basic data can be divided into three categories: point data, surface data and volume data, point data mainly wells and wells dot attribute information, mainly a variety of surface data plan and structural map, mainly seismic volume data volume data, seismic inversion data volume. point data. All of the work area well abscissa, ordinate, make up the heart altitude, logging subdivision layer, inclined wells trajectory parameters, logs, well point attribute data, including rock, sandstone thickness, effective thickness, porosity, permeability and oil saturation. plane data. Longitudinal stratigraphic thickness larger gold belt region, seismic interpretation provides 10 structure surface (NG, D1, D2, D3, S1S, S1Z, S1X, S31, S32, S33), hierarchical data interpolation utilizing well in the modeling process calculated data structure surface of the remaining 52; the other side is sedimentary microfacies data plan data; third surface is oil and gas reservoirs plane data distribution, which is the oil and gas area plan area. Seismic interpretation of fault data, fault and fault data includes polygon data slice. Border and grid modeling accuracy Different mesh types, mesh size, mesh orientation, grid scale model simulation accuracy, reliability will have a huge impact. Therefore, to ensure the accuracy of the simulation results and rationality, to determine a reasonable grid system is a prerequisite for simulation studies. Corner points of the grid is a new type of grid, which uses eight vertex coordinates irregular hexahedral describe the 3rd International Conference on Management, Education, Information and Control (MEICI 2015
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