2,736 research outputs found

    How smooth is the stock market integration of CEE-3?

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    We study the stock market integration of emerging CEE-3 stock markets (namely, the Czech, Hungarian, and Polish markets) and hypothesize that this process has been gradual over time. As a proxy for integration, co-movements with three stock market indices that represent the developed markets (i.e., MSCI Germany, the Dow Jones Euro Stoxx 50, and MSCI World) are estimated using the standard, asymmetric, and corrected DCC-GARCH model. A smooth transition logistic trend model is then fitted to the dynamic correlations to examine the integration process. Evidence of strengthening relationships among the markets under study is provided.http://deepblue.lib.umich.edu/bitstream/2027.42/132978/1/wp1079.pd

    Quantitative 3d reconstruction from scanning electron microscope images based on affine camera models

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    Scanning electron microscopes (SEMs) are versatile imaging devices for the micro-and nanoscale that find application in various disciplines such as the characterization of biological, mineral or mechanical specimen. Even though the specimen’s two-dimensional (2D) properties are provided by the acquired images, detailed morphological characterizations require knowledge about the three-dimensional (3D) surface structure. To overcome this limitation, a reconstruction routine is presented that allows the quantitative depth reconstruction from SEM image sequences. Based on the SEM’s imaging properties that can be well described by an affine camera, the proposed algorithms rely on the use of affine epipolar geometry, self-calibration via factorization and triangulation from dense correspondences. To yield the highest robustness and accuracy, different sub-models of the affine camera are applied to the SEM images and the obtained results are directly compared to confocal laser scanning microscope (CLSM) measurements to identify the ideal parametrization and underlying algorithms. To solve the rectification problem for stereo-pair images of an affine camera so that dense matching algorithms can be applied, existing approaches are adapted and extended to further enhance the yielded results. The evaluations of this study allow to specify the applicability of the affine camera models to SEM images and what accuracies can be expected for reconstruction routines based on self-calibration and dense matching algorithms. © MDPI AG. All rights reserved

    Towards improving WEBSOM with multi-word expressions

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    Dissertação para obtenção do Grau de Mestre em Engenharia InformáticaLarge quantities of free-text documents are usually rich in information and covers several topics. However, since their dimension is very large, searching and filtering data is an exhaustive task. A large text collection covers a set of topics where each topic is affiliated to a group of documents. This thesis presents a method for building a document map about the core contents covered in the collection. WEBSOM is an approach that combines document encoding methods and Self-Organising Maps (SOM) to generate a document map. However, this methodology has a weakness in the document encoding method because it uses single words to characterise documents. Single words tend to be ambiguous and semantically vague, so some documents can be incorrectly related. This thesis proposes a new document encoding method to improve the WEBSOM approach by using multi word expressions (MWEs) to describe documents. Previous research and ongoing experiments encourage us to use MWEs to characterise documents because these are semantically more accurate than single words and more descriptive

    Texture direction analysis of micro-topographies using fractal geometry

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    In recent years fractal geometry has been repeatedly shown to help describe and characterize micro-topographies. Important properties of micro-topographies include roughness or texture direction. Consequently, in this work, fractal geometry is investigated to determine texture direction. For this purpose, synthetic data and real height maps of different micro-topographies are evaluated using the fractal power spectrum density method. The results are compared with a manual determination of the texture direction and determining the texture direction according to ISO 25 178 using the S td parameter. The results show that the fractal method is more accurate than the currently standardized method. Another advantage is that secondary texture directions can be detected. Thus, the fractal method is well suited for characterizing micro-topographies and can complement existing parameters from ISO 25 178

    RGB-D microtopography: A comprehensive dataset for surface analysis and characterization techniques

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    The dataset presented contains microtopographies of various materials and processing methods. These microtopographies were measured using a Confocal Laser Scanning Microscope, which provides RGB-D data. This means the dataset comprises accurate height maps for each measurement and microscopic RGB images. The height maps can be used to quantify and characterize small-scale surface features such as pits and grooves, surface roughness, texture direction, and surface anisotropy. These features can significantly impact a material's properties and behavior, making them essential in many fields, such as biomaterials and tribology. Additionally, the dataset contains metadata about the specimens and the measurement conditions, such as material, surface processing method, roughness, and optical magnification. Therefore, this dataset provides an opportunity to develop and test surface classification and characterization algorithms
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