1,785 research outputs found

    What determines large scale galaxy clustering: halo mass or local density?

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    Using dark matter simulations we show how halo bias is determined by local density and not by halo mass. This is not totally surprising, as according to the peak-background split model, local density is the property that constraints bias at large scales. Massive haloes have a high clustering because they reside in high density regions. Small haloes can be found in a wide range of environments which determine their clustering amplitudes differently. This contradicts the assumption of standard Halo Occupation Distribution (HOD) models that the bias and occupation of haloes is determined solely by their mass. We show that the bias of central galaxies from semi-analytic models of galaxy formation as a function of luminosity and colour is not correctly predicted by the standard HOD model. Using local density instead of halo mass the HOD model correctly predicts galaxy bias. These results indicate the need to include information about local density and not only mass in order to correctly apply HOD analysis in these galaxy samples. This new model can be readily applied to observations and has the advantage that the galaxy density can be directly observed, in contrast with the dark matter halo mass.Comment: 11 pages, 9 figure

    Measuring the growth of matter fluctuations with third-order galaxy correlations

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    Measurements of the linear growth factor DD at different redshifts zz are key to distinguish among cosmological models. One can estimate the derivative dD(z)/dln(1+z)dD(z)/d\ln(1+z) from redshift space measurements of the 3D anisotropic galaxy two-point correlation ξ(z)\xi(z), but the degeneracy of its transverse (or projected) component with galaxy bias bb, i.e. ξ(z) D2(z)b2(z)\xi_{\perp}(z) \propto\ D^2(z) b^2(z), introduces large errors in the growth measurement. Here we present a comparison between two methods which break this degeneracy by combining second- and third-order statistics. One uses the shape of the reduced three-point correlation and the other a combination of third-order one- and two-point cumulants. These methods use the fact that, for Gaussian initial conditions and scales larger than 2020 h1h^{-1}Mpc, the reduced third-order matter correlations are independent of redshift (and therefore of the growth factor) while the third-order galaxy correlations depend on bb. We use matter and halo catalogs from the MICE-GC simulation to test how well we can recover b(z)b(z) and therefore D(z)D(z) with these methods in 3D real space. We also present a new approach, which enables us to measure DD directly from the redshift evolution of second- and third-order galaxy correlations without the need of modelling matter correlations. For haloes with masses lower than 101410^{14} h1h^{-1}M_\odot, we find 1010% deviations between the different estimates of DD, which are comparable to current observational errors. At higher masses we find larger differences that can probably be attributed to the breakdown of the bias model and non-Poissonian shot noise.Comment: 24 pages, 20 figures, 2 tables, accepted for publication in MNRA

    Transformer-based Multi-Modal Learning for Multi Label Remote Sensing Image Classification

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    In this paper, we introduce a novel Synchronized Class Token Fusion (SCT Fusion) architecture in the framework of multi-modal multi-label classification (MLC) of remote sensing (RS) images. The proposed architecture leverages modality-specific attention-based transformer encoders to process varying input modalities, while exchanging information across modalities by synchronizing the special class tokens after each transformer encoder block. The synchronization involves fusing the class tokens with a trainable fusion transformation, resulting in a synchronized class token that contains information from all modalities. As the fusion transformation is trainable, it allows to reach an accurate representation of the shared features among different modalities. Experimental results show the effectiveness of the proposed architecture over single-modality architectures and an early fusion multi-modal architecture when evaluated on a multi-modal MLC dataset. The code of the proposed architecture is publicly available at https://git.tu-berlin.de/rsim/sct-fusion.Comment: Accepted at IEEE International Geoscience and Remote Sensing Symposium 202

    Voraussetzung und Entwicklung des Studienganges 'Bild- und Toningenieur' an der Hochschule Mittweida

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    The investigation of the production environment factors through the prism of the game process

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    У сучасному світі широко використовується гейміфікація, як один з найбільш ефективних підходів в навчанні. Гейміфікація застосовується з метою залучення користувачів, підвищення їхньої зацікавленості у вирішенні прикладних завдань. Однією з найбільш ефективних методик виступає ділова гра. У процесі її моделювання визначається проблемна ситуація, і мета гри полягає в пошуку шляхів її вирішення. Ділові ігри застосовуються як в освітній, так і діловій сферах. Важливе значення ділових ігор полягає також в тому, що вони сприяють встановленню відносин співробітництва викладача і студентів, обумовлюють формування позитивного емоційно-психологічного клімату на заняттях. Розроблена і впроваджена в навчальний процес робота "Office Explorer" - це візуальний інструмент у вивченні впливу факторів виробничого середовища і трудового процесу на стан здоров'я людини і навколишнього середовища. Створена така універсальна програма, яка в ігровій формі доступно, не нав'язливо донесе інформацію до студента, заставить проаналізувати, засвоїти, зробити правильні висновки, обрати необхідні засоби і заходи захисту від впливу шкідливих чинників виробничого середовища і трудового процесу. Програма "Office Explorer" об'єднала в собі всі ці вимоги до комп'ютерних лабораторних робіт і стала незамінним інструментом в засвоєнні знань і практичних навичок з дисциплін "Безпека життєдіяльності" та "Основ охорони праці". Реалізований підхід є найсучаснішим рішенням висвітленої проблеми сучасних заходів навчання та оцінювання знань студентів ВНЗ. Використання цього підходу дозволяє автоматизувати навчальний процес, а також готує майбутнього спеціаліста до умов вирішення реальних проблем. Використання подібних робіт при різних формах навчання дуже важливо і необхідно в сучасних умовах.In the modern world, gaming is widely used as one of the most effective approaches in the teaching. Gaming is used to attract users, increase their interest in solving applied problems. One of the most effective techniques is the business game. In the process of its simulation, the problem situation is determined, and the purpose of the game is to find ways to solve it. Business games are applied both in educational and business spheres. The importance of business games is also that they contribute to the establishment of relations between the teacher and students, which determine the formation of a positive emotional and psychological climate in the classes. The "Office Explorer" work developed and implemented in the educational process is a visual tool in studying the influence of the working environment factors and the working process on the condition of human health and the environment. The Office Explorer program combines all these requirements with computer labs and has become an indispensable tool in acquiring knowledge and practical skills in the disciplines "Security of Life" and "Fundamentals of Occupational Safety". The implemented approach is the most up-to-date solution of the illuminated problem of modern educational measures and assessment of students' knowledge of universities. Using this approach allows you to automate the learning process, as well as prepare a future specialist for the conditions for solving real problems. The using of such works in various forms of training is very important and necessary in the modern conditions
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