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The semi-hierarchical Dirichlet process and its application to clustering homogeneous distributions

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arXiv 2020年

作者： Beraha, Mario Guglielmi, Alessandra Quintana, Fernando A. Department of Mathematics Politecnico di Milano Italy Department of Computer Science Università di Bologna Italy Department of Statistics Pontificia Universidad Católica de Chile Chile ANID - Millennium Science Initiative Program Millennium Nucleus Center for the Discovery of Structures in Complex Data

Assessing homogeneity of distributions is an old problem that has received considerable attention, especially in the nonparametric Bayesian literature. To this effect, we propose the semi-hierarchical Dirichlet process, a novel hierarchical prior that extends the hierarchical Dirichlet process of Teh et al. (2006) and that avoids the degeneracy issues of nested processes recently described by Camerlenghi et al. (2019a). We go beyond the simple yes/no answer to the homogeneity question and embed the proposed prior in a random partition model;this procedure allows us to give a more comprehensive response to the above question and in fact find groups of populations that are internally homogeneous when I ≥ 2 such populations are considered. We study theoretical properties of the semi-hierarchical Dirichlet process and of the Bayes factor for the homogeneity test when I = 2. Extensive simulation studies and applications to educational data are also discussed. Copyright © 2020, The Authors. All rights reserved.

关键词： statistics

Environmental modelling of CO concentration using AI-based approach supported with filters feature extraction: A direct and inverse chemometrics-based simulation

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Sustainable Chemistry for the Environment

Sustainable Chemistry for the Environment 2023年 2卷

作者： Usman, A.G. Usanase, Natacha Abba, S.I. Ozsahin, Ilker Uzun, Berna Yassin, Mohamed A. Rahman, Syed Masiur Ozsahin, Dilber Uzun Operational Research Centre in Healthcare Near East University Mersin 10 Turkey Department of Analytical Chemistry Faculty of Pharmacy Near East University Mersin 10 Turkey Interdisciplinary Research Centre for Membranes and Water Security King Fahd University of Petroleum and Minerals Dhahran 31261 Saudi Arabia Department of Biomedical Engineering Faculty of Engineering Near East University Mersin 10 Turkey Department of Statistics Carlos III Madrid University Getafe Madrid Spain Department of Mathematics Faculty of Arts and Sciences Near East University Mersin 10 Turkey Medical Diagnostic Imaging Department College of Health Sciences University of Sharjah Sharjah United Arab Emirates Applied Research Center for Environment and Marine Studies King Fahd University of Petroleum & Minerals (KFUPM) Dhahran 31261 Saudi Arabia Research Institute for Medical and Health Sciences University of Sharjah Sharjah United Arab Emirates

This study explored the first direct and inverse modelling of Carbon monoxide (CO) concentration by applying three different computational approaches namely, Least Square-boost (L-Boost), Hammerstein Weiner (HW), and Multi-variate regression (MVR) models for modelling CO using Sulphur dioxide (SO₂), Nitrogen dioxide (NO₂) and Ozone (O₃). Two filters feature extraction methods were used in the input-combinations selection, which was classified into the direct modelling approach (C1) and inverse modelling approach (C2). Four different statistical metrics, including Nash-Sutcliffe efficiency, Person correlation coefficient, mean absolute error and mean absolute percentage error was used in evaluating the performance of the models. Based on the performance skills of the models, it is indicated that the direct modelling approach showed superior performance to the inverse approach. Furthermore, the non-linear models (HW and L-Boost) depict higher performance skills than the linear MVR model. Overall, the L-Boost-C1 models showed higher performance based on statistical metrics. © 2023 The Authors

关键词： Artificial intelligence CO Environmental modelling Filters feature extraction Pollutant

An embedded-hybridized discontinuous Galerkin method for the coupled Stokes-Darcy system

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arXiv 2019年

作者： Cesmelioglu, Aycil Rhebergen, Sander Wells, Garth N. Department of Mathematics and Statistics Oakland University Michigan United States Department of Applied Mathematics University of Waterloo Canada Department of Engineering University of Cambridge United Kingdom

We introduce an embedded-hybridized discontinuous Galerkin (EDG-HDG) method for the coupled Stokes-Darcy system. This EDG-HDG method is a pointwise mass-conserving discretization resulting in a divergence-conforming velocity field on the whole domain. In the proposed scheme, coupling between the Stokes and Darcy domains is achieved naturally through the EDG-HDG facet variables. A priori error analysis shows optimal convergence rates, and that the velocity error does not depend on the pressure. The error analysis is verified through numerical examples on unstructured grids for different orders of polynomial *** Codes 65N12, 65N15, 65N30, 76D07, 76S99 Copyright © 2019, The Authors. All rights reserved.

关键词： Galerkin methods

Thermo-economic and environmental evaluation of thin film evaporation using novel metal-organic frameworks to enhance solar desalination performance

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Process Safety and Environmental Protection 2025年 199卷

作者： Sharshir, Swellam W. Abdo, Mohamed R. Yusuf, Kareem El-Naggar, Ahmed A. Joseph, Abanob Ismail, M. Elsaid, Ashraf Mimi El-Samadony, M.O.A. Abdelfatah, Mahmoud El-Shaer, Abdelhamid Yuan, Zhanhui College of Materials Engineering Fujian Agriculture and Forestry University Fuzhou350002 China Mechanical Engineering Department Faculty of Engineering Kafrelsheikh University Kafrelsheikh33516 Egypt Department of Physics and Engineering Mathematics Faculty of Engineering University of Kafrelsheikh Kafrelsheikh Egypt Department of Chemistry College of Science King Saud University Riyadh11451 Saudi Arabia Physics Department Faculty of Science Kafrelsheikh University Kafrelsheikh33516 Egypt Nano Science and Technology Program Faculty of Science Kafrelsheikh University Kafrelsheikh33516 Egypt Department of Mechanical Engineering Faculty of Engineering Suez University SuezP.O. Box 43221 Egypt Refrigeration and Air Conditioning Technology Department Faculty of Technology and Education Helwan University CairoP.O. Box 11282 Egypt Mechanical Power Engineering Department Faculty of Engineering Tanta University Tanta City Egypt

The growing shortage of freshwater resources has spurred the development of innovative and sustainable desalination technologies. This study presents a thermo-economic analysis of an innovative hemispherical solar still (HSS) enhanced with a novel Metal-Organic Framework (MOF), specifically Iron-Aluminum Benzene Tricarboxylate. The MOF was characterized through structural, morphological, and optical investigations and integrated into the HSS using two enhancement methods: (I) as a nanofluid (MOF-NF) at a 1 wt% concentration in the feedwater, and (II) as a heat localization material (MOF-HL) by dispersing it on a black cotton wick that spans the basin surface. An external condenser (EC) was added to further enhance condensation in a subsequent configuration. Three identical HSS systems were used for comparative performance evaluation: a baseline unit (CHSS) and two modified systems, one with a condenser and one without. The results indicated that both MOF-based approaches significantly improved the thermal performance and freshwater yield of the HSS. Notably, the MOF-HL configuration outperformed the MOF-NF configuration across all performance metrics. The configuration designated as MOF-HL-EC achieved the highest rate of freshwater production, with a 96.16 % increase in distillate productivity compared to the CHSS. Additionally, this configuration exhibited exergy and energy efficiencies of 3.18 % and 61.1 %, respectively—improvements of 80.85 % and 95.72 % over the traditional system. Economically, the MOF-HL-EC configuration reduced the production cost of distilled water to 0.0115$ per liter, marking a reduction of 25.29 %. © 2025 The Institution of Chemical Engineers

关键词： Iron analysis

Modeling The Amount of Insurance Claim using Gamma Linear Mixed Model with AR (1) random effect

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Journal of Physics: Conference Series 2021年第1期1863卷

作者： F A Adam A Kurnia I G P Purnaba I W Mangku A M Soleh Program Vokasi Universitas Indonesia Depok 16424 Indonesia Department of Statistics IPB University Bogor 16680 Indonesia Department of Mathematics IPB University Bogor 16680 Indonesia

The amount of insurance claims is continuous data and is positive so it is usually assumed to have gamma distribution. Usually, Generalized Linear Model (GLM)'s approach is used since the gamma distribution is a member of the exponential family. In case there is a random effect in modeling, then GLM can be extended to Generalized Linear Mixed Model (GLMM). This study models the amount of insurance claims with the most GLMM's approach using two random effects, namely the region and time of the occurrence which is assumed to follow a first-order autoregressive process. The h-likelihood method is used to estimate the regression parameters and the variance parameters. A simulation study is carried out with an evaluation using the average relative bias and the average MSE. An application study which is conducted to model the amount of insurance claims in a certain region and time based on the 2014 profile of risk and loss of motor vehicle insurance in Indonesia is also carried out.

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Atomistic-to-meso multi-scale data-driven graph surrogate modeling of dislocation glide

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arXiv 2020年

作者： de Moraes, Eduardo Augusto Barros Suzuki, Jorge L. Zayernouri, Mohsen Department of Mechanical Engineering Department of Computational Mathematics Science and Engineering Michigan State University 428 S Shaw Ln East LansingMI48824 United States Department of Mechanical Engineering Department of Statistics and Probability Michigan State University 428 S Shaw Ln East LansingMI48824 United States

From their birth in the manufacturing process, materials inherently contain defects that affect the mechanical behavior across multiple length and time-scales, including vacancies, dislocations, voids and cracks. Understanding, modeling, and real-time simulation of the underlying stochastic micro-structure defect evolution is therefore vital towards multi-scale coupling and propagating numerous sources of uncertainty from atomistic to eventually aging continuum mechanics. We develop a graph-based surrogate model of dislocation glide for computation of dislocation mobility. We model an edge dislocation as a random walker, jumping between neighboring nodes of a graph following a Poisson stochastic process. The network representation functions as a coarse-graining of a molecular dynamics simulation that provides dislocation trajectories for an empirical computation of jump rates. With this construction, we recover the original atomistic mobility estimates, with remarkable computational speed-up and accuracy. Furthermore, the underlying stochastic process provides the statistics of dislocation mobility associated to the original molecular dynamics simulation, allowing an efficient propagation of material parameters and uncertainties across the scales. © 2020, CC BY.

关键词： Stochastic systems

Automating the Practice of Science – Opportunities, Challenges, and Implications

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arXiv 2024年

作者： Musslick, Sebastian Bartlett, Laura K. Chandramouli, Suyog H. Dubova, Marina Gobet, Fernand Griffiths, Thomas L. Hullman, Jessica King, Ross D. Nathan Kutz, J. Lucas, Christopher G. Mahesh, Suhas Pestilli, Franco Sloman, Sabina J. Holmes, William R. Institute of Cognitive Science Osnabrück University Osnabrück49090 Germany Department of Cognitive Linguistic & Psychological Sciences Brown University ProvidenceRI02912 United States Centre for Philosophy of Natural and Social Science London School of Economics Lakatos Building Houghton Street LondonWC2A 2AE United Kingdom AaltoFI-00076 Finland Department of Computing Science University of Alberta 8900 114 St NW EdmontonABT6G 2S4 Canada Cognitive Science Program Indiana University 1101 E 10th St BloomingtonIN47405 United States School of Psychology University of Roehampton LondonSW15 4JD United Kingdom Departments of Psychology and Computer Science Princeton University PrincetonNJ United States Department of Computer Science Northwestern University IL United States Department of Chemical Engineering and Biotechnology University of Cambridge CambridgeCB3 0AS United Kingdom Department of Computer Science and Engineering Chalmers University of Technology Gothenburg412 96 Sweden Department of Applied Mathematics and Electrical and Computer Engineering University of Washington Seattle98195 United States School of Informatics University of Edinburgh 10 Crichton St. EH8 9AB United Kingdom Department of Materials Science and Engineering University of Toronto Canada Department of Psychology Department of Neuroscience The University of Texas AustinTX United States Department of Computer Science University of Manchester M13 9PL United Kingdom

Automation transformed various aspects of our human civilization, revolutionizing industries and streamlining processes. In the domain of scientific inquiry, automated approaches emerged as powerful tools, holding promise for accelerating discovery, enhancing reproducibility, and overcoming the traditional impediments to scientific progress. This article evaluates the scope of automation within scientific practice and assesses recent approaches. Furthermore, it discusses different perspectives to the following questions: Where do the greatest opportunities lie for automation in scientific practice?;What are the current bottlenecks of automating scientific practice?;and What are significant ethical and practical consequences of automating scientific practice? By discussing the motivations behind automated science, analyzing the hurdles encountered, and examining its implications, this article invites researchers, policymakers, and stakeholders to navigate the rapidly evolving frontier of automated scientific practice. © 2024, CC BY.

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Exploring variations in design methods for service design of insulated concrete wall panels

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engineering Structures 2025年 340卷

作者： Maryam Al-Bayati Salam Al-Rubaye Fray F. Pozo-Lora Brennan Bean Marc Maguire MER Engineers Inc. 925 Factory Rd #A Dayton 45434 OH United States Durham School of Architectural Engineering & Construction University of Nebraska – Lincoln 1110 S 67th St Omaha 68182 NE United States Department of Mathematics and Statistics Utah State University 3900 Old Main Hill Logan 84322 UT United States

Concrete sandwich wall panels (CSWPs) have been designed and constructed since the early 1920s with a variety of shear ties, dimensions, and methods; however, thermal bridges have been a problem for architects, owners, and engineers. The wythe connector industry has developed plastic connectors that have gradually replaced concrete solid sections and steel connectors due to their superior thermal efficiency, but there has yet to be a generally accepted method for predicting the behavior of sandwich wall panels in structural engineering practice or codes. Still, many methods have been used routinely since the early 1960s for designing CSWPs and are generally limited to elastic methods. This study investigates the precision and accuracy of the elastic methods currently used to predict the flexural performance of concrete sandwich wall panels subjected to out-of-plane loading using testing data available in the literature. In this manuscript, the analysis is performed within the elastic range using eight different analysis methods in the literature and compared against the results of 96 full-scale specimens constructed with commercially available wythe connectors and unique connectors only found in research and different concrete properties and panel dimensions. The results indicate that discrete methods, such as the BSM, MBM, and SSBT, yield similar cracking load and deflections at cracking, whereas continuous connecting medium methods, like Allen and Holmberg & Plem methods, produce scattered results. Future research in CSWPs must address the need for flexural testing representing the modern tilt-up and precast concrete panels, especially for those over 6 meters long with unequal wythe thicknesses, large insulation thicknesses, and high-strength concrete.

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A bayesian multilevel random-effects model for estimating noise in image sensors

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arXiv 2020年

作者： Riutort-Mayol, Gabriel Gomez-Rubio, Virgilio Marques-Mateu, Angel Jośe Luis Lerma Ĺopez-Qúilez, Antonio Department of Cartographic Engineering Geodesy and Photogrammetry Universitat Politècnica de València Spain Department of Mathematics Universidad de Castilla-La Mancha Albacete Spain Department of Statistics and Operations Research Universitat de València Burjassot Spain

Sensor noise sources cause differences in the signal recorded across pixels in a single image and across multiple images. This paper presents a Bayesian approach to decomposing and characterizing the sensor noise sources involved in imaging with digital cameras. A Bayesian probabilistic model based on the (theoretical) model for noise sources in image sensing is fitted to a set of a time-series of images with different reflectance and wavelengths under controlled lighting conditions. The image sensing model is a complex model, with several interacting components dependent on reflectance and wavelength. The properties of the Bayesian approach of defining conditional dependencies among parameters in a fully probabilistic model, propagating all sources of uncertainty in inference, makes the Bayesian modeling framework more attractive and powerful than classical methods for approaching the image sensing model. A feasible correspondence of noise parameters to their expected theoretical behaviors and well calibrated posterior predictive distributions with a small root mean square error for model predictions have been achieved in this study, thus showing that the proposed model accurately approximates the image sensing model. The Bayesian approach could be extended to formulate further components aimed at identifying even more specific parameters of the imaging *** Codes 62P30, 62P35, 62F15, 62J05 Copyright © 2020, The Authors. All rights reserved.

关键词： Hierarchical systems