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Probing solutions to the S8 tension with galaxy clustering

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arXiv 2023年

作者： Carrilho, Pedro Moretti, Chiara Tsedrik, Maria Institute for Astronomy The University of Edinburgh Royal Observatory EdinburghEH9 3HJ United Kingdom SISSA - International School for Advanced Studies Via Bonomea 265 Trieste34136 Italy Centro Nazionale "High Performance Computer Big Data and Quantum Computing" Italy

The current discrepancy between the CMB and weak lensing measurements of the amplitude of matter fluctuations, the so-called S8 tension, has attracted a great deal of recent attention, as it may show a crack in the ΛCDM model of cosmology. We review the evidence for this tension and describe potential solutions, focusing on extensions of the standard cosmological model, including interacting dark energy and modified gravity. We present a likelihood analysis of the BOSS DR12 data, probing these alternative models as well as ΛCDM. From this analysis, we show hints of non-standard cosmology compatible with those seen in weak lensing observations, demonstrating that interacting dark energy or modified gravity can explain them successfully. We then discuss the robustness of these results to analysis choices, as well as future paths to confirm them with additional data and further distinguish between models. © 2023, CC BY.

关键词： Cosmology

Deep Perspective Transformation Based Vehicle Localization on Bird’s Eye View

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arXiv 2023年

作者： Mahyar, Abtin Motamednia, Hossein Rahmati, Dara Department of Computer and Data Sciences Shahid Beheshti University Tehran Iran High Performance Computing Laboratory School of Computer Science Institute for Research in Fundamental Sciences Tehran Iran Faculty of Computer Science and engineering Shahid Beheshti University Tehran Iran

An accurate understanding of a self-driving vehicle’s surrounding environment is crucial for its navigation system. To enhance the effectiveness of existing algorithms and facilitate further research, it is essential to provide comprehensive data to the routing system. Traditional approaches rely on installing multiple sensors to simulate the environment, leading to high costs and complexity. In this paper, we propose an alternative solution by generating a top-down representation of the scene, enabling the extraction of distances and directions of other cars relative to the ego vehicle. We introduce a new synthesized dataset that offers extensive information about the ego vehicle and its environment in each frame, providing valuable resources for similar downstream tasks. Additionally, we present an architecture that transforms perspective view RGB images into bird’s-eye-view maps with segmented surrounding vehicles. This approach offers an efficient and cost-effective method for capturing crucial environmental information for self-driving cars. 1 © 2023, CC BY.

关键词： Birds

Topic-Guided Self-Introduction Generation for Social Media Users

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arXiv 2023年

作者： Xu, Chunpu Li, Jing Li, Piji Yang, Min Department of Computing The Hong Kong Polytechnic University Hong Kong College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics China Shenzhen Key Laboratory for High Performance Data Mining Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences China

Millions of users are active on social media. To allow users to better showcase themselves and network with others, we explore the auto-generation of social media self-introduction, a short sentence outlining a user’s personal interests. While most prior work profiles users with tags (e.g., ages), we investigate sentence-level self-introductions to provide a more natural and engaging way for users to know each other. Here we exploit a user’s tweeting history to generate their self-introduction. The task is non-trivial because the history content may be lengthy, noisy, and exhibit various personal interests. To address this challenge, we propose a novel unified topic-guided encoder-decoder (UTGED) framework;it models latent topics to reflect salient user interest, whose topic mixture then guides encoding a user’s history and topic words control decoding their self-introduction. For experiments, we collect a large-scale Twitter dataset, and extensive results show the superiority of our UTGED to the advanced encoder-decoder models without topic modeling. 1 © 2023, CC BY.

关键词： User profile

Experimental Investigation and Thermodynamic Calculation of Phase Equilibria in The Ternary Fe-Ta-Si System

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SSRN

SSRN 2023年

作者： Liu, Xingjun Cui, Yunrui Huang, Liangfeng Yang, Mujin Yang, Feng Zhang, Jinbin Guo, Yihui Lu, Yong Wang, Cuiping College of Materials Fujian Key Laboratory of Surface and Interface Engineering for High Performance Materials Xiamen University Xiamen361005 China Xiamen Key Laboratory of High-Performance Metals and Materials Xiamen University Xiamen361005 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Materials Science and Engineering Institute of Materials Genome & Big Data Harbin Institute of Technology Shenzhen518055 China

Two isothermal sections of the Fe-Ta-Si ternary system at 1100 °C and 900 °C in the whole composition range have been experimentally determined combined with EPMA and XRD techniques. Except for these known ternary G, E, and V phases, a new ternary compound named X was detected with the composition region about 27.1-29.9 at. % Fe, 30.6-31.7 at. % Ta and 39.5-41.2 at. % Si. Si has an extensive solubility in the Fe2Ta phase, and the solubility of Fe in the Ta2Si phase tends to be parallel to the Fe-Si side. Based on the experimental results in this work, the Fe-Ta-Si ternary system has been assessed using the CALPHAD method. A set of reliable thermodynamic parameters for the Fe-Ta-Si system was obtained. The current thermodynamic description is in good agreement with available experimental data. The calculated liquidus projection and invariant reaction scheme in the Fe-Ta-Si ternary system were presented. The present work can provide essential experimental and thermodynamic data for the establishment of the G-phase strengthen alloy database. © 2023, The Authors. All rights reserved.

关键词： Ternary systems

Improving Software Defined Network Controllers in a Multi-Vendor Environment

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SSRN

SSRN 2023年

作者： Deneke, Bereketeab Berhanu Beyene, Asrat Mulatu Haile, Endalew Ayenew Department of Computer Science School of Graduate Studies St. Mary’s University Addis Ababa Ethiopia High Performance Computing & Big Data Analytics CoE Department of Electrical and Computer Engineering Addis Ababa Science and Technology University Addis Ababa Ethiopia Adama Science and Technology University School of Electrical Engineering and Computing Electrical Power and Control Engineering Adama Ethiopia

Software Defined Networking (SDN) is an emerging networking paradigm with the potential to foster innovation through programmable networks. SDNs are characterized by the separation of control and data planes where, in a logically centralized controller, it’s possible to make routing decisions on behalf of forwarding elements. For this, there are different protocols used like Open Flow, Forward and Control Element Separation (FORCES), Path Computation Element Protocol (PCEP), Network Configuration Protocol (NETCONF), and Interface to Routing System (IRS). Border Gateway Protocol (BGP) is one such protocol that can enable the network programmability promised by SDNs. The controllers used in BGP as control plane protocol leverages RESTCONF (RFC 8040) as management plane protocol to interact with physical routers, switches, and network service firewalls. Therefore, the aim of this work is to improve the performance of SDN controllers using BGP enabling a multi-vendor environment without requiring infrastructure upgrade showcasing how interoperability can be achieved. The proposed system is implemented using OpenDaylight controllers. The performance of the prototype is evaluated using Latency, Throughput, CPU consumption, and TTL (Time to Live). Based on the simulation results it is observed that the SDN controllers that use BGP show improvements in terms of Latency and Throughput. © 2023, The Authors. All rights reserved.

关键词： Controllers

Towards virtual painting recolouring using Vision Transformer on X-Ray Fluorescence datacubes

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arXiv 2024年

作者： Bombini, Alessandro Bofías, Fernando García-Avello Giambi, Francesca Ruberto, Chiara Via Bruno Rossi 1 Sesto Fiorentino50019 Italy ICSC Centro Nazionale di Ricerca in High Performance Computing Big Data & Quantum Computing Via Magnanelli 2 Casalecchio di Reno40033 Italy Università degli Studi di Firenze P.za di San Marco 4 Firenze50121 Italy Dipartimento di Fisica Università degli Studi di Firenze Via Giovanni Sansone 1 Sesto Fiorentino50019 Italy

In this contribution, we define (and test) a pipeline to perform virtual painting recolouring using raw data of X-Ray Fluorescence (XRF) analysis on pictorial artworks. To circumvent the small dataset size, we generate a synthetic dataset, starting from a database of XRF spectra;furthermore, to ensure a better generalisation capacity (and to tackle the issue of in-memory size and inference time), we define a Deep Variational Embedding network to embed the XRF spectra into a lower dimensional, K-Means friendly, metric space. We thus train a set of models to assign coloured images to embedded XRF images. We report here the devised pipeline performances in terms of visual quality metrics, and we close on a discussion on the results. © 2024, CC BY.

关键词： Network embeddings

Narrow bandwidth gamma comb from nonlinear Compton scattering using the polarization gating technique

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arXiv 2020年

作者： Valialshchikov, Maksim A. Yu. Kharin, V. Rykovanov, S.G. High Performance Computing and Big Data Laboratory Skolkovo Institute of Science and Technology Moscow Russia

Nonlinear Compton scattering is a promising source of bright gamma-rays. Using readily available intense laser pulses to scatter off the energetic electrons, on the one hand, allows to significantly increase the total photon yield, but on the other hand, leads to a dramatic spectral broadening of fundamental emission line as well as its harmonics due to the laser pulse shape induced ponderomotive effects. In this paper we propose to avoid ponderomotive broadening in harmonics by using the polarization gating technique - a well-known method to construct a laser pulse with temporally varying polarization. We show that by restricting harmonic emission only to the region near the peak of the pulse, where the polarization is linear, it is possible to generate a bright narrow bandwidth comb in the gamma region. Copyright © 2020, The Authors. All rights reserved.

关键词： Gamma rays

Gradient Amplification: An Efficient Way to Train Deep Neural Networks

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big data Mining and Analytics 2020年第3期3卷 196-207页

作者： Sunitha Basodi Chunyan Ji Haiping Zhang Yi Pan Department of Computer Science Georgia State UniversityAtlantaGA 30302USA Center for High Performance Computing Joint Engineering Research Center for Health Big Data Intelligent Analysis TechnologyShenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Improving performance of deep learning models and reducing their training times are ongoing challenges in deep neural *** are several approaches proposed to address these challenges,one of which is to increase the depth of the neural *** deeper networks not only increase training times,but also suffer from vanishing gradients problem while *** this work,we propose gradient amplification approach for training deep learning models to prevent vanishing gradients and also develop a training strategy to enable or disable gradient amplification method across several epochs with different learning *** perform experiments on VGG-19 and Resnet models(Resnet-18 and Resnet-34),and study the impact of amplification parameters on these models in *** proposed approach improves performance of these deep learning models even at higher learning rates,thereby allowing these models to achieve higher performance with reduced training time.

关键词： deep learning gradient amplification learning rate backpropagation vanishing gradients

21cmEMU: an emulator of 21cmFAST summary observables

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arXiv 2023年

作者： Breitman, Daniela Mesinger, Andrei Murray, Steven G. Prelogović, David Qin, Yuxiang Trotta, Roberto Piazza dei Cavalieri 7 PI Pisa56125 Italy School of Earth and Space Exploration Arizona State University TempeAZ United States School of Physics University of Melbourne ParkvilleVIC3010 Australia Australia Via Bonomea 265 Trieste34136 Italy Centro Nazionale "High Performance Computer Big Data and Quantum Computing"

Recent years have witnessed rapid progress in observations of the Epoch of Reionization (EoR). These have enabled high-dimensional inference of galaxy and intergalactic medium (IGM) properties during the first billion years of our Universe. However, even using efficient, semi-numerical simulations, traditional inference approaches that compute 3D lightcones on-the-fly can take 105 core hours. Here we present 21cmEMU: an emulator of several summary observables from the popular 21cmFAST simulation code. 21cmEMU takes as input nine parameters characterizing EoR galaxies, and outputs the following summary statistics: (i) the IGM mean neutral fraction;(ii) the 21-cm power spectrum;(iii) the mean 21-cm spin temperature;(iv) the sky-averaged (global) 21-cm signal;(v) the ultraviolet (UV) luminosity functions (LFs);and (vi) the Thomson scattering optical depth to the cosmic microwave background (CMB). All observables are predicted with sub-percent median accuracy, with a reduction of the computational cost by a factor of over 104. After validating inference results, we showcase a few applications, including: (i) quantifying the relative constraining power of different observational datasets;(ii) seeing how recent claims of a late EoR impact previous inferences;and (iii) forecasting upcoming constraints from the sixth observing season of the Hydrogen Epoch of Reionization Array (HERA) telescope. 21cmEMU is publicly-available, and is included as an alternative simulator in the public 21cmMC sampler. Copyright © 2023, The Authors. All rights reserved.

关键词： Cosmology