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Oktavian MR, Nistor J, Gruenwald JT, Xu Y. Integrating core physics and machine learning for improved parameter prediction in boiling water reactor operations. Sci Rep 2024; 14:5835. [PMID: 38461347 PMCID: PMC10924948 DOI: 10.1038/s41598-024-56388-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 03/06/2024] [Indexed: 03/11/2024] Open
Abstract
This study introduces a novel method for enhancing Boiling Water Reactor (BWR) operation simulations by integrating machine learning (ML) models with conventional simulation techniques. The ML model is trained to identify and correct errors in low-fidelity simulation outputs, traditionally derived from core physics computations. These corrections aim to align the low-fidelity results closely with high-fidelity data. Precise predictions of nuclear reactor parameters like core eigenvalue and power distribution are crucial for efficient fuel management and adherence to technical specifications. Current high-fidelity transport calculations, while accurate, are impractical for real-time predictions due to extensive computational demands. Our approach, therefore, utilizes the standard two-step simulation process-assembly-level lattice physics calculations followed by whole-core nodal diffusion computations-to generate initial results, which are then refined using the ML-based error correction model. The methodology focuses on improving simulation accuracy in regular BWR operations rather than developing a universal ML predictor for reactor physics. By training an advanced neural network model on the difference in high-fidelity and low-fidelity simulations, the model can reduce the nodal power error from low-fidelity simulations to around 1% on average and the core eigenvalue down to under 100 pcm. This result is under the condition of the normal variations of control rod pattern and core flow rate changes in standard BWR operations used in the training and evaluation of the machine learning model. This work suggests a promising approach for achieving more accurate, computationally feasible simulation solutions in nuclear reactor operation and management.
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Affiliation(s)
- M R Oktavian
- Blue Wave AI Labs, 1281 Win Hentschel Blvd, West Lafayette, IN, 47906, USA.
- School of Nuclear Engineering, Purdue University, 363 North Grant Street, #5281, West Lafayette, IN, 47907, USA.
| | - J Nistor
- Blue Wave AI Labs, 1281 Win Hentschel Blvd, West Lafayette, IN, 47906, USA
- Department of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, IN, 47907, USA
| | - J T Gruenwald
- Blue Wave AI Labs, 1281 Win Hentschel Blvd, West Lafayette, IN, 47906, USA
| | - Y Xu
- School of Nuclear Engineering, Purdue University, 363 North Grant Street, #5281, West Lafayette, IN, 47907, USA
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Granchi N, Intonti F, Florescu M, García PD, Gurioli M, Arregui G. Q-Factor Optimization of Modes in Ordered and Disordered Photonic Systems Using Non-Hermitian Perturbation Theory. ACS PHOTONICS 2023; 10:2808-2815. [PMID: 37602292 PMCID: PMC10436348 DOI: 10.1021/acsphotonics.3c00510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Indexed: 08/22/2023]
Abstract
The quality factor, Q, of photonic resonators permeates most figures of merit in applications that rely on cavity-enhanced light-matter interaction such as all-optical information processing, high-resolution sensing, or ultralow-threshold lasing. As a consequence, large-scale efforts have been devoted to understanding and efficiently computing and optimizing the Q of optical resonators in the design stage. This has generated large know-how on the relation between physical quantities of the cavity, e.g., Q, and controllable parameters, e.g., hole positions, for engineered cavities in gaped photonic crystals. However, such a correspondence is much less intuitive in the case of modes in disordered photonic media, e.g., Anderson-localized modes. Here, we demonstrate that the theoretical framework of quasinormal modes (QNMs), a non-Hermitian perturbation theory for shifting material boundaries, and a finite-element complex eigensolver provide an ideal toolbox for the automated shape optimization of Q of a single photonic mode in both ordered and disordered environments. We benchmark the non-Hermitian perturbation formula and employ it to optimize the Q-factor of a photonic mode relative to the position of vertically etched holes in a dielectric slab for two different settings: first, for the fundamental mode of L3 cavities with various footprints, demonstrating that the approach simultaneously takes in-plane and out-of-plane losses into account and leads to minor modal structure modifications; and second, for an Anderson-localized mode with an initial Q of 200, which evolves into a completely different mode, displaying a threefold reduction in the mode volume, a different overall spatial location, and, notably, a 3 order of magnitude increase in Q.
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Affiliation(s)
- Nicoletta Granchi
- Department
of Physics, University of Florence, via Sansone 1, I-50019 Sesto Fiorentino, FI, Italy
- European
Laboratory for Nonlinear Spectroscopy, via Nello Carrara 1, I-50019 Sesto Fiorentino, FI, Italy
| | - Francesca Intonti
- Department
of Physics, University of Florence, via Sansone 1, I-50019 Sesto Fiorentino, FI, Italy
- European
Laboratory for Nonlinear Spectroscopy, via Nello Carrara 1, I-50019 Sesto Fiorentino, FI, Italy
| | - Marian Florescu
- Advanced
Technology Institute and Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, U.K.
| | - Pedro David García
- Instituto
de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Calle Sor Juana Inés de la
Cruz 3, 28049 Madrid, Spain
| | - Massimo Gurioli
- Department
of Physics, University of Florence, via Sansone 1, I-50019 Sesto Fiorentino, FI, Italy
- European
Laboratory for Nonlinear Spectroscopy, via Nello Carrara 1, I-50019 Sesto Fiorentino, FI, Italy
| | - Guillermo Arregui
- Department
of Electrical and Photonics Engineering, DTU Electro, Technical University of Denmark, Building 343, DK-2800 Kgs. Lyngby, Denmark
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Oktavian M, Nistor J, Gruenwald J, Xu Y. Preliminary development of machine learning-based error correction model for low-fidelity reactor physics simulation. ANN NUCL ENERGY 2023. [DOI: 10.1016/j.anucene.2023.109788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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Sassaroli A, Tommasi F, Cavalieri S, Martelli F. Fluence rate directly derived from photon pathlengths: a tool for Monte Carlo simulations in biomedical optics. BIOMEDICAL OPTICS EXPRESS 2023; 14:148-162. [PMID: 36698672 PMCID: PMC9842009 DOI: 10.1364/boe.477339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/25/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
In biomedical optics, the mean fluence rate of photons, assessed in a sub-volume of a propagating medium, is classically obtained in Monte Carlo simulations by taking into account the power deposited by the absorbed photons in the sub-volume. In the present contribution, we propose and analytically demonstrate an alternative method based on the assessment of the mean pathlength traveled by all the photons inside the sub-volume. Few practical examples of its applications are given. This method has the advantage of improving, in many cases, the statistics and the convergence of the Monte Carlo simulations. Further, it also works when the absorption coefficient is nil and for a non-constant spatial distribution of the absorption coefficient inside the sub-volume. The proposed approach is a re-visitation of a well-known method applied in radiation and nuclear physics in the context of radiative transfer, where it can be derived in a more natural manner.
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Affiliation(s)
- Angelo Sassaroli
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Federico Tommasi
- Dipartimento di Fisica e Astronomia dell’Università degli Studi di Firenze, via Giovanni Sansone 1, 50019 Sesto Fiorentino, Italy
| | - Stefano Cavalieri
- Dipartimento di Fisica e Astronomia dell’Università degli Studi di Firenze, via Giovanni Sansone 1, 50019 Sesto Fiorentino, Italy
| | - Fabrizio Martelli
- Dipartimento di Fisica e Astronomia dell’Università degli Studi di Firenze, via Giovanni Sansone 1, 50019 Sesto Fiorentino, Italy
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Tommasi F, Fini L, Focardi S, Martelli F, Santini G, Cavalieri S. On the mean path length invariance property for random walks of animals in open environment. Sci Rep 2022; 12:19800. [PMID: 36396773 PMCID: PMC9672306 DOI: 10.1038/s41598-022-24361-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 11/14/2022] [Indexed: 11/18/2022] Open
Abstract
Random walks are common in nature and are at the basis of many different phenomena that span from neutrons and light scattering to the behaviour of animals. Despite the evident differences among all these phenomena, theory predicts that they all share a common fascinating feature known as Invariance Property (IP). In a nutshell, IP means that the mean length of the total path of a random walker inside a closed domain is fixed by the geometry and size of the medium. Such a property has been demonstrated to hold not only in optics, but recently also in the field of biology, by studying the movement of bacteria. However, the range of validity of such a universal property, strictly linked to the fulfilment of equilibrium conditions and to the statistical distributions of the steps of the random walkers, is not trivial and needs to be studied in different contexts, such as in the case of biological entities occupied in random foraging in an open environment. Hence, in this paper the IP in a virtual medium inside an open environment has been studied by using actual movements of animals recorded in nature. In particular, we analysed the behaviour of a grazer mollusc, the chiton Acanthopleura granulata. The results depart from those predicted by the IP when the dimension of the medium increases. Such findings are framed in both the condition of nonequilibrium of the walkers, which is typical of animals in nature, and the characteristics of actual animal movements.
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Affiliation(s)
- Federico Tommasi
- Dipartimento di Fisica e Astronomia, Università di Firenze, Via Giovanni Sansone 1, 50019, Sesto Fiorentino, Italy.
| | - Lorenzo Fini
- Dipartimento di Fisica e Astronomia, Università di Firenze, Via Giovanni Sansone 1, 50019, Sesto Fiorentino, Italy
| | - Stefano Focardi
- Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy
| | - Fabrizio Martelli
- Dipartimento di Fisica e Astronomia, Università di Firenze, Via Giovanni Sansone 1, 50019, Sesto Fiorentino, Italy
| | - Giacomo Santini
- Dipartimento di Biologia, Università di Firenze, Via Madonna del Piano 6, 50019, Sesto Fiorentino, Italy
| | - Stefano Cavalieri
- Dipartimento di Fisica e Astronomia, Università di Firenze, Via Giovanni Sansone 1, 50019, Sesto Fiorentino, Italy
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Efficient computation of the steady-state and time-domain solutions of the photon diffusion equation in layered turbid media. Sci Rep 2022; 12:18979. [PMID: 36347893 PMCID: PMC9643457 DOI: 10.1038/s41598-022-22649-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 10/18/2022] [Indexed: 11/09/2022] Open
Abstract
Accurate and efficient forward models of photon migration in heterogeneous geometries are important for many applications of light in medicine because many biological tissues exhibit a layered structure of independent optical properties and thickness. However, closed form analytical solutions are not readily available for layered tissue-models, and often are modeled using computationally expensive numerical techniques or theoretical approximations that limit accuracy and real-time analysis. Here, we develop an open-source accurate, efficient, and stable numerical routine to solve the diffusion equation in the steady-state and time-domain for a layered cylinder tissue model with an arbitrary number of layers and specified thickness and optical coefficients. We show that the steady-state ([Formula: see text] ms) and time-domain ([Formula: see text] ms) fluence (for an 8-layer medium) can be calculated with absolute numerical errors approaching machine precision. The numerical implementation increased computation speed by 3 to 4 orders of magnitude compared to previously reported theoretical solutions in layered media. We verify our solutions asymptotically to homogeneous tissue geometries using closed form analytical solutions to assess convergence and numerical accuracy. Approximate solutions to compute the reflected intensity are presented which can decrease the computation time by an additional 2-3 orders of magnitude. We also compare our solutions for 2, 3, and 5 layered media to gold-standard Monte Carlo simulations in layered tissue models of high interest in biomedical optics (e.g. skin/fat/muscle and brain). The presented routine could enable more robust real-time data analysis tools in heterogeneous tissues that are important in many clinical applications such as functional brain imaging and diffuse optical spectroscopy.
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Pattelli L, Mazzamuto G. Experimental imaging and Monte Carlo modeling of ultrafast pulse propagation in thin scattering slabs. JOURNAL OF BIOMEDICAL OPTICS 2022; 27:083020. [PMID: 35655345 PMCID: PMC9162504 DOI: 10.1117/1.jbo.27.8.083020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 05/20/2022] [Indexed: 06/15/2023]
Abstract
SIGNIFICANCE Most radiative transport problems in turbid media are typically associated with mm or cm scales, leading to typical time scales in the range of hundreds of ps or more. In certain cases, however, much thinner layers can also be relevant, which can dramatically alter the overall transport properties of a scattering medium. Studying scattering in these thin layers requires ultrafast detection techniques and adaptations to the common Monte Carlo (MC) approach. AIM We aim to discuss a few relevant aspects for the simulation of light transport in thin scattering membranes, and compare the obtained numerical results with experimental measurements based on an all-optical gating technique. APPROACH A thin membrane with controlled scattering properties based on polymer-dispersed TiO2 nanoparticles is fabricated for experimental validation. Transmittance measurements are compared against a custom open-source MC implementation including specific pulse profiles for tightly focused femtosecond laser pulses. RESULTS Experimental transmittance data of ultrafast pulses through a thin scattering sample are compared with MC simulations in the spatiotemporal domain to retrieve its scattering properties. The results show good agreement also at short distances and time scales. CONCLUSIONS When simulating light transport in scattering membranes with thicknesses in the orders of tens of micrometer, care has to be taken when describing the temporal, spatial, and divergence profiles of the source term, as well as the possible truncation of step length distributions, which could be introduced by simple strategies for the generation of random exponentially distributed variables.
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Affiliation(s)
- Lorenzo Pattelli
- Istituto Nazionale di Ricerca Metrologica (INRiM), Torino, Italy
- European Laboratory for Nonlinear Spectroscopy (LENS), Sesto Fiorentino, Italy
| | - Giacomo Mazzamuto
- European Laboratory for Nonlinear Spectroscopy (LENS), Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica (INO), CNR, Sesto Fiorentino, Italy
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Binzoni T, Martelli F. Monte Carlo simulations in anomalous radiative transfer: tutorial. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2022; 39:1053-1060. [PMID: 36215535 DOI: 10.1364/josaa.454463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/28/2022] [Indexed: 06/16/2023]
Abstract
Anomalous radiative transfer (ART) theory represents a generalization of classical radiative transfer theory. The present tutorial aims to show how Monte Carlo (MC) codes describing the transport of photons in anomalous media can be implemented. We show that the heart of the method involves suitably describing, in a "non-classical" manner, photon steps starting from fixed light sources or from boundaries separating regions of the medium with different optical properties. To give a better sense of the importance of these particular photon step lengths, we also show numerically that the described approach is essential in preserving the invariance property for light propagation. An interesting byproduct of the MC method for ART is that it allows us to simplify the structure of "classical" MC codes, utilized, for example, in biomedical optics.
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Sassaroli A, Tommasi F, Cavalieri S, Fini L, Liemert A, Kienle A, Binzoni T, Martelli F. Two-step verification method for Monte Carlo codes in biomedical optics applications. JOURNAL OF BIOMEDICAL OPTICS 2022; 27:JBO-210404GRR. [PMID: 35445592 PMCID: PMC9020254 DOI: 10.1117/1.jbo.27.8.083018] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/21/2022] [Indexed: 06/14/2023]
Abstract
SIGNIFICANCE Code verification is an unavoidable step prior to using a Monte Carlo (MC) code. Indeed, in biomedical optics, a widespread verification procedure for MC codes is still missing. Analytical benchmarks that can be easily used for the verification of different MC routines offer an important resource. AIM We aim to provide a two-step verification procedure for MC codes enabling the two main tasks of an MC simulator: (1) the generation of photons' trajectories and (2) the intersections of trajectories with boundaries separating the regions with different optical properties. The proposed method is purely based on elementary analytical benchmarks, therefore, the correctness of an MC code can be assessed with a one-sample t-test. APPROACH The two-step verification is based on the following two analytical benchmarks: (1) the exact analytical formulas for the statistical moments of the spatial coordinates where the scattering events occur in an infinite medium and (2) the exact invariant solutions of the radiative transfer equation for radiance, fluence rate, and mean path length in media subjected to a Lambertian illumination. RESULTS We carried out a wide set of comparisons between MC results and the two analytical benchmarks for a wide range of optical properties (from non-scattering to highly scattering media, with different types of scattering functions) in an infinite non-absorbing medium (step 1) and in a non-absorbing slab (step 2). The deviations between MC results and exact analytical values are usually within two standard errors (i.e., t-tests not rejected at a 5% level of significance). The comparisons show that the accuracy of the verification increases with the number of simulated trajectories so that, in principle, an arbitrary accuracy can be obtained. CONCLUSIONS Given the simplicity of the verification method proposed, we envision that it can be widely used in the field of biomedical optics.
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Affiliation(s)
- Angelo Sassaroli
- Tufts University, Department of Biomedical Engineering, Medford, Massachusetts, United States
| | - Federico Tommasi
- Dipartimento di Fisica e Astronomia dell’Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - Stefano Cavalieri
- Dipartimento di Fisica e Astronomia dell’Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - Lorenzo Fini
- Dipartimento di Fisica e Astronomia dell’Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - André Liemert
- Institut für Lasertechnologien in der Medizin und Meßtechnik an der Universität Ulm (ILM), Ulm, Germany
| | - Alwin Kienle
- Institut für Lasertechnologien in der Medizin und Meßtechnik an der Universität Ulm (ILM), Ulm, Germany
| | - Tiziano Binzoni
- University of Geneva, Department of Basic Neurosciences, Geneva, Switzerland
- University Hospital, Department of Radiology and Medical Informatics, Geneva, Switzerland
| | - Fabrizio Martelli
- Dipartimento di Fisica e Astronomia dell’Università degli Studi di Firenze, Sesto Fiorentino, Italy
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