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arXiv 2024年

作者： Bhatt, Maulik Gallerani, Simona Ferrara, Andrea Mazzucchelli, Chiara D'Odorico, Valentina Valentini, Milena Zana, Tommaso Farina, Emanuele Paolo Chakraborty, Srija Scuola Normale Superiore Piazza dei Cavalieri 7 PisaI-56126 Italy Instituto de Estudios Astrofísicos Facultad de Ingeniería y Ciencias Universidad Diego Portales Avenida Ejercito Libertador 441 Santiago Chile INAF - Osservatorio Astronomico di Trieste via Tiepolo 11 TriesteI-34131 Italy IFPU - Institute for Fundamental Physics of the Universe Via Beirut 2 Trieste34014 Italy Astronomy Unit Department of Physics University of Trieste via Tiepolo 11 TriesteI-34131 Italy ICSC - Italian Research Center on High Performance Computing Big Data and Quantum Computing Italy Dipartimento di Fisica Sapienza Università di Roma Piazzale Aldo Moro 5 Roma00185 Italy Gemini Observatory NSF's NOIRLab 670 N A'ohoku Place HiloHI96720 United States

Context. Observations of z ∼ 6 quasars powered by supermassive black holes (SMBHs;MBH ∼ 108−10 Mo) challenge our current understanding of early black hole (BH) formation and evolution. The advent of the James Webb Space Telescope (JWST) has enabled the study of massive BHs (MBHs;MBH ∼ 106−7 Mo) up to z ∼ 11, thus bridging the properties of z ∼ 6 quasars to their ancestors. Aims. The JWST spectroscopic observations of GN-z11, a well-known z = 10.6 star-forming galaxy, have been interpreted with the presence of a super-Eddington (Eddington ratio ≡ λEdd ∼ 5.5) accreting MBH. To test this hypothesis, we used a zoom-in cosmological simulation of galaxy formation and BH co-evolution. Methods. We first tested the simulation results against the observed probability distribution function (PDF) of λEdd found in z ∼ 6 quasars. Then, in the simulation we selected the BHs that satisfy the following criteria: (a) 10 BH > 106 Mo. Next, we applied the extreme value statistics to the PDF of λEdd resulting from the simulation. Results. We find that the probability of observing a z ∼ 10 − 11 MBH accreting with λEdd ∼ 5.5 in the volume surveyed by JWST is very low ( © 2024, CC BY.

关键词： Uncertainty analysis

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Entanglement-Induced Barren Plateaus

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PRX Quantum 2021年第4期2卷 040316-040316页

作者： Carlos Ortiz Marrero Mária Kieferová Nathan Wiebe Data Sciences and Analytics Group Pacific Northwest National Laboratory Richland Washington 99354 USA Centre for Quantum Computation and Communication Technology Centre for Quantum Software and Information University of Technology Sydney New South Wales 2007 Australia Department of Computer Science University of Toronto Ontario M5S 1A1 Canada High Performance Computing Group Pacific Northwest National Laboratory Richland Washington 99354 USA

We argue that an excess in entanglement between the visible and hidden units in a quantum neural network can hinder learning. In particular, we show that quantum neural networks that satisfy a volume law in the entanglement entropy will give rise to models that are not suitable for learning with high probability. Using arguments from quantum thermodynamics, we then show that this volume law is typical and that there exists a barren plateau in the optimization landscape due to entanglement. More precisely, we show that for any bounded objective function on the visible layers, the Lipshitz constants of the expectation value of that objective function will scale inversely with the dimension of the hidden subsystem with high probability. We show how this can cause both gradient-descent and gradient-free methods to fail. We note that similar problems can happen with quantum Boltzmann machines, although stronger assumptions on the coupling between the hidden and/or visible subspaces are necessary. We highlight how pretraining such generative models may provide a way to navigate these barren plateaus.

关键词： Machine learning Quantum algorithms

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On the effects of parameters on galaxy properties in CAMELS and the predictability of Ωm

arXiv

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arXiv 2025年

作者： Contardo, Gabriella Trotta, Roberto Gioia, Serafina Di Hogg, David W. Villaescusa-Navarro, Francisco Center for Astrophysics and Cosmology University of Nova Gorica Ajdovščina Slovenia Trieste Italy ICSC - Centro Nazionale di Ricerca in High Performance Computing Big Data e Quantum Computing Via Magnanelli 2 Bologna Italy Astrophysics Group Physics Department Blackett Lab Imperial College London Prince Consort Road LondonSW7 2AZ United Kingdom INAF – Osservatorio Astronomico di Trieste Via G. B. Tiepolo 11 TriesteI-34143 Italy Trieste Italy Center for Cosmology and Particle Physics Department of Physics New York University New YorkNY United States Max-Planck-Institut für Astronomie Heidelberg Germany Center for Computational Astrophysics Flatiron Institute New YorkNY United States Department of Astrophysical Sciences Peyton Hall Princeton University NJ08544-0010 United States

Recent analyses of cosmological hydrodynamic simulations from CAMELS have shown that machine learning models can predict the parameter describing the total matter content of the universe, Ωm, from the features of a single galaxy. We investigate the statistical properties of two of these simulation suites, IllustrisTNG and ASTRID, confirming that Ωm induces a strong displacement on the distribution of galaxy features. We also observe that most other parameters have little to no effect on the distribution, except for the stellar-feedback parameter ASN1, which introduces some near-degeneracies that can be broken with specific features. These two properties explain the predictability of Ωm. We use Optimal Transport to further measure the effect of parameters on the distribution of galaxy properties, which is found to be consistent with physical expectations. However, we observe discrepancies between the two simulation suites, both in the effect of Ωm on the galaxy properties and in the distributions themselves at identical parameter values. Thus, although Ωm’s signature can be easily detected within a given simulation suite using just a single galaxy, applying this result to real observational data may prove significantly more challenging. © 2025, CC BY.

关键词： Galaxies

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On the range of validity of perturbative models for galaxy clustering and its uncertainty

arXiv

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arXiv 2023年

作者： Gambardella, Giosuè Biagetti, Matteo Moretti, Chiara Sefusatti, Emiliano Institute for Fundamental Physics of the Universe Via Beirut 2 Trieste34151 Italy Campus UAB Carrer de Can Magrans s/n Barcelona08193 Spain Area Science Park Località Padriciano 99 Trieste34149 Italy Scuola Internazionale di Studi Superiori Avanzati via Bonomea 265 Trieste34136 Italy Istituto Nazionale di Astrofisica Osservatorio Astronomico di Trieste via Tiepolo 11 Trieste34143 Italy Istituto Nazionale di Fisica Nucleare Sezione di Trieste via Valerio 2 Trieste34127 Italy Centro Nazionale "High Performance Computer Big Data and Quantum Computing" Italy

We explore the reach of an analytical model at one-loop in Perturbation Theory (PT) to accurately describe measurements of the galaxy power spectrum from numerical simulations in redshift space. We consider the validity range in terms of three different diagnostics: 1) the goodness of fit;2) a figure-of-bias quantifying the error in recovering the fiducial value of a cosmological parameter;3) an internal consistency check of the theoretical model quantifying the running of the model parameters with the scale cut. We consider different sets of measurements corresponding to an increasing cumulative simulation volume in redshift space. For each volume we define a median value and the associated scatter for the largest wavenumber where the model is valid (the k-reach of the model). We find, as a rather general result, that the median value of the reach decreases with the simulation volume, as expected since the smaller statistical errors provide a more stringent test for the model. This is true for all the three definitions considered, with the one given in terms of the figure-of-bias providing the most stringent scale cut. More interestingly, we also find that the error associated with the k-reach value is quite large, with a significant probability of being as low as 0.1 ℎMpc−1 (or, more generally, up to 40% smaller than the median) for all the simulation volumes considered. We explore as well the additional information on the growth rate parameter encoded in the power spectrum hexadecapole, compared to the analysis of monopole and quadrupole, as a function of simulation volume. While our analysis is, in many ways, rather simplified, we find that the gain in the determination of the growth rate is quite small in absolute value and well within the statistical error on the corresponding figure of merit. Copyright © 2023, The Authors. All rights reserved.

关键词： Power spectrum

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Lane Marking Detection Algorithm Based on high-Precision Map 6th

Lane Marking Detection Algorithm Based on High-Precision Map

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6th International Conference on data Science, ICDS 2019

作者： Yao, Haichang Chen, Chen Liu, Shangdong Li, Kui Ji, Yimu Wang, Ruchuan School of Computer and Software Nanjing Institute of Industry Technology Nanjing210023 China School of Computer Science Nanjing University of Posts and Telecommunications Nanjing210023 China Institute of High Performance Computing and Big Data Nanjing University of Posts and Telecommunications Nanjing210003 China Nanjing Center of HPC China Nanjing210003 China Jiangsu HPC and Intelligent Processing Engineer Research Center Nanjing210003 China

ISBN: (纸本)9789811528095

In case of sharp road illumination changes, bad weather such as rain, snow or fog, wear or missing of the lane marking, the reflective water stain on the road surface, the shadow obstruction of the tree, and mixed lane markings and other signs, missing detection or wrong detection will occur for the traditional lane marking detection algorithm. In this manuscript, a lane marking detection algorithm based on high-precision map is proposed. The basic principle of the algorithm is to use the centimeter-level high-precision positioning combined with high-precision map data to complete the detection of lane markings. The experimental results show that the algorithm has lower false detection rate in case of bad road conditions, and the algorithm is robust. © Springer Nature Singapore Pte Ltd 2020.

关键词： Road and street markings

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Pream: Enhancing HPC storage system performance with pre-allocated metadata management mechanism 21

Pream: Enhancing HPC storage system performance with pre-all...

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21st IEEE International Conference on high performance computing and Communications, 17th IEEE International Conference on Smart City and 5th IEEE International Conference on data Science and Systems, HPCC/SmartCity/DSS 2019

作者： Li, Hongbo Cheng, Peng Chen, Zhiguang Xiao, Nong School of Data and Computer Science Sun Yat-Sen University Guangzhou China State Key Laboratory of High Performance Computing National University of Defense Technology Changsha China

ISBN: (纸本)9781728120584

With the convergence of high performance computing (HPC) and big data, processing a large volume of scientific data on HPC systems is getting increased attentions. However, supporting these data-intensive workloads on HPC systems that are geared for compute-intensive workloads presents a new challenge in data management. Typical HPC systems consist of a large collection of compute nodes and use parallel file systems (PFSs) for persistent data storage. Although PFSs provide concurrent I/O bandwidth and perform well for large sequential write/read requests, its performance is bottlenecked by expensive metadata operations. Moreover, data-intensive applications with bursty I/O patterns or generate a large number of temporary files exacerbate the shortcomings. In this paper, we propose Pream, a light-weight metadata management framework that aim to address these challenges. Pream targets scenarios of supporting data-intensive workloads that generates a huge number of temporary files on diskless compute nodes. Pream pre-allocates file metadata from the metadata server, and manages these metadata locally to accelerate metadata operations. While newly created temporary files keep residing in PFSs, open/create requests of these temporary files can be handled by Pream locally without connecting with PFSs. Our evaluation demonstrates that Pream can outperform Lustre in many workloads and reduce latency of metadata operation efficiently. © 2019 IEEE.

关键词： Metadata

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Neural posterior estimation with guaranteed exact coverage: The ringdown of GW150914

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Physical Review D 2023年第4期108卷 044029-044029页

作者： Marco Crisostomi Kallol Dey Enrico Barausse Roberto Trotta SISSA Via Bonomea 265 34136 Trieste Italy and INFN Sezione di Trieste 34127 Trieste Italy IFPU—Institute for Fundamental Physics of the Universe Via Beirut 2 34014 Trieste Italy School of Physics Indian Institute of Science Education and Research Thiruvananthapuram Maruthamala PO Vithura Thiruvananthapuram 695551 Kerala India Physics Department Imperial College London Prince Consort Road SW7 2AZ London United Kingdom Centro Nazionale “High Performance Computer Big Data and Quantum Computing” Via Magnanelli 2 40033 Casalecchio di Reno (BO) Italy

We analyze the ringdown phase of the first detected black-hole merger, GW150914, using a simulation-based inference pipeline based on masked autoregressive flows. We obtain approximate marginal posterior distributions for the ringdown parameters, namely the mass, spin, and the amplitude and phases of the dominant mode and its first overtone. Thanks to the locally amortized nature of our method, we are able to calibrate our posteriors with injected simulations, producing posterior regions with guaranteed (i.e., exact) frequentist coverage of the true values. For GW150914, our calibrated posteriors provide only mild evidence (∼2σ) for the presence of an overtone, even if the ringdown is assumed to start at the peak of the amplitude.

关键词： Classical black holes General relativity Gravitational waves

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Turbulent pressure support in galaxy clusters Impact of the hydrodynamical solver

arXiv

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arXiv 2024年

作者： Groth, Frederick Valentini, Milena Steinwandel, Ulrich P. Vallés-Pérez, David Dolag, Klaus Universitäts-Sternwarte Fakultät für Physik Ludwig-Maximilians-Universität München Scheinerstr. 1 München81679 Germany Astronomy Unit Department of Physics University of Trieste via Tiepolo 11 TriesteI-34131 Italy INAF - Osservatorio Astronomico di Trieste via Tiepolo 11 TriesteI-34131 Italy ICSC - Italian Research Center on High Performance Computing Big Data and Quantum Computing via Magnanelli 2 Casalecchio di Reno40033 Italy Center for Computational Astrophysics Flatiron Institute 162 Fifth Avenue New YorkNY10010 United States Departament d’Astronomia i Astrofísica Universitat de València C/Doctor Moliner 50 Burjassot ValènciaE-46100 Spain Max-Planck-Institut für Astrophysik Karl-Schwarzschild-Straße 1 Garching85741 Germany

Context. The amount of turbulent pressure in galaxy clusters is still debated, especially as for the impact of the dynamical state and the hydro-method used for simulations. Aims. We study the turbulent pressure fraction in the intra cluster medium of massive galaxy clusters. We aim to understand the impact of the hydrodynamical scheme, analysis method, and dynamical state on the final properties of galaxy clusters from cosmological simulations. Methods. We perform non-radiative simulations of a set of zoom-in regions of seven galaxy clusters with Meshless Finite Mass (MFM) and Smoothed Particle Hydrodynamics (SPH). We use three different analysis methods based on: (i) the deviation from hydrostatic equilibrium, (ii) the solenoidal velocity component obtained by a Helmholtz-Hodge decomposition, and (iii) the small-scale velocity obtained through a multi-scale filtering approach. We split the sample of simulated clusters into active and relaxed clusters. Results. Our simulations predict an increased turbulent pressure fraction for active compared to relaxed clusters. This is especially visible for the velocity-based methods. For these, we also find increased turbulence for the MFM simulations compared to SPH, consistent with findings from more idealized simulations. The predicted non-thermal pressure fraction varies between a few percent for relaxed clusters and ≈ 13% for active ones within the cluster center and increases towards the outskirts. No clear trend with redshift is visible. Conclusions. Our analysis quantitatively assesses the importance played by the hydrodynamical scheme and the analysis method to determine the non-thermal/turbulent pressure fraction. While our setup is relatively simple (non-radiative runs), our simulations show agreement with previous, more idealized simulations, and make a step further toward the understanding of turbulence. Copyright © 2024, The Authors. All rights reserved.

关键词： Cosmology

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Weakly supervised learning for textbook question answering

TechRxiv

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TechRxiv 2021年

作者： Ma, Jie Chai, Qi Huang, Jingyue Liu, Jun You, Yang Zheng, Qinghua National Engineering Lab for Big Data Analytics School of Computer Science and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China Shaanxi Province Key Laboratory of Satellite and Terrestrial Network Tech. R&D School of Computer Science and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China The High Performance Computing for Artificial intelligence Lab Department of Computer Science National University of Singapore 117417 Singapore

Textbook Question Answering (TQA) is the task of answering diagram and non-diagram questions given large multimodal contexts consisting of abundant text and diagrams. Deep text understandings and effective learning of diagram semantics are important for this task due to its specificity. In this paper, we propose a Weakly Supervised learning method for TQA (WSTQ), which regards the incompletely accurate results of essential intermediate procedures for this task as supervision to develop Text Matching (TM) and Relation Detection (RD) tasks and then employs the tasks to motivate itself to learn strong text comprehension and excellent diagram semantics respectively. Specifically, we apply the result of text retrieval to build positive as well as negative text pairs. In order to learn deep text understandings, we first pre-train the text understanding module of WSTQ on TM and then fine-tune it on TQA. We build positive as well as negative relation pairs by checking whether there is any overlap between the items/regions detected from diagrams using object detection. The RD task forces our method to learn the relationships between regions, which are crucial to express the diagram semantics. We train WSTQ on RD and TQA simultaneously, i.e., multitask learning, to obtain effective diagram semantics and then improve the TQA performance. Extensive experiments are carried out on CK12-QA and AI2D to verify the effectiveness of WSTQ. Experimental results show that our method achieves significant accuracy improvements of 5.02% and 4.12% on test splits of the above datasets respectively than the current state-of-the-art baseline. We have released our code on https://***/dr-majie/WSTQ. © 2021, CC BY.

关键词： Semantics

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Revealing Interfacial Properties of Inorganic Molecular Crystal Sb2o3 and Monolayer Mos2

SSRN

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SSRN 2023年

作者： Liu, Qin Zuo, Yang He, Jingyu Zeng, Minggang Yang, Tong Zhou, Jun Yang, Yulin Song, Ting Ting Wang, Shijie Yang, Ming College of Physics and Space Science China West Normal University Nanchong637002 China Department of Applied Physics The Hong Kong Polytechnic University Hung Hom Hong Kong Institute of High-Performance Computing A∗STAR 1 Fusionopolis Way Singapore138632 Singapore Institute of Materials Research and Engineering A ∗ STAR 2 Fusionopolis Way Singapore138634 Singapore Fujian Provincial Key Laboratory of Optoelectronic Technology and Devices School of Optoelectronic and Communication Engineering Xiamen University of Technology Xiamen361024 China Research Centre on Data Sciences & Artificial Intelligence The Hong Kong Polytechnic University Hung Hom Hong Kong

Inorganic molecule crystal Sb2O3 has been identified as a promising high-k dielectric for direct integration with the two-dimensional semiconductor MoS2. However, a comprehensive understanding of this van der Waals (vdW) interface is still lacking, impeding its applications in high-performance nanoelectronics. In this study, we employ first-principles calculations to elucidate the interfacial interaction and electronic properties of the Sb2O3/monolayer MoS2 interface. We find that a high-performance quasi-vdW interface can be formed between Sb2O3 and monolayer MoS2, as evidenced by weak interfacial interaction, a dangling-bond-free interface, insignificant electron-hole puddle redistribution, and the preserved semiconducting properties of monolayer MoS2. Notably, the interface exhibits a remarkable defect tolerance capability during integration, as Sb2O3 cluster vacancies (the dominant defect in Sb2O3) neither introduce mid-gap states nor significantly affect the interface properties. Besides, our study reveals an asymmetric type-I band alignment at the interface, where the conduction band offset is sufficiently large to minimize electron tunneling. Our work offers a comprehensive understanding of the vdW interface between Sb2O3 and monolayer MoS2, which could potentially advance the development of inorganic molecular crystals as high-k dielectrics for high-performance two-dimensional electronic devices. © 2023, The Authors. All rights reserved.

关键词： Antimony compounds

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