Capability Of Code Research Articles

SIMULATION OF TRANSIENT PROCESS ON WWER-1000 USING COUPLED APPROACH

Research and modeling of thermohydraulic processes in NPP equipment is necessary for a deep and improved justification of reliable and safe operation of nuclear installations. Taking into account the accumulated experience and the latest technologies, the study of thermohydraulic processes is developing in the direction of applying innovative approaches to conducting both experimental studies and expanding the calculation capabilities of thermohydraulic codes. The article presents an approach to the decomposition of the thermohydraulic model of the WWER-1000 reactor plant on submodels, which are calculated in coupling with separate instances of the system thermohydraulic code RELAP5/Mod 3.2. Coupling is implemented using a specially developed module. This approach allows you to "bypass" the internal limitations of RELAP5 in the number of components (hydrodynamic volumes, thermal structures, "trips" and control variables) that can be used for computational analysis. As a result, it becomes possible to achieve a higher degree of detail for the entire reactor installation. In addition, the article confirms the possibility of applying the previously developed coupling module to such a non-equilibrium model as a nuclear reactor model. At the same time, the use of the RELAP5 model as a reactor model makes it possible to avoid inaccuracies that arise when applying assumptions about the transverse profiles of the input variables of the CFX model, as well as to perform the validation of the RELAP5 model of the RU loops. Coupled calculation of stationary and transient mode of reactor installation WWER-1000 is performed. The reliability of calculation results obtained in conjugation is evaluated by comparing them with the results of autonomous calculations in RELAP5. The analysis of the results of computational modeling confirms the possibility of applying the developed coupling module to such a non-equilibrium model as a model of a nuclear reactor, and also confirms the correctness of the RELAP5 model of the loops of the reactor plant obtained on the basis of the modification of the full-fledged RELAP5 model.

Role of electrostatic perturbation on kinetic resistive wall mode with application to spherical tokamak

A more complete non-perturbative magnetohydrodynamic (MHD)-kinetic hybrid formulation is developed by including the perturbed electrostatic potential δφ in the particle Lagrangian. The fluid-like counter-parts of the hybrid equations, in the Chew-Goldberger-Low high-frequency limit, are also derived and utilized to test the new toroidal implementation in the MARS-K code. Application of the updated non-perturbative hybrid model for a high-β spherical tokamak plasma in MAST finds that the perturbed electrostatic potential generally plays a minor role in the n = 1 (n is the toroidal mode number) resistive wall mode instability. The effect of δφ is largely destabilizing, with the growth rate of the instability increased by several (up to 20) percent as compared to the case without including δφ. A similar relative change is also obtained for the kinetic-induced resonant field amplification effect at high-β in the MAST plasma considered. The updated capability of the MARS-K code allows quantitative exploration of drift kinetic effects on various MHD instabilities and the antenna-driven plasma response where the electrostatic perturbation, coupled to magnetic perturbations, may play important roles.

VAMPyR-A high-level Python library for mathematical operations in a multiwavelet representation.

Wavelets and multiwavelets have lately been adopted in quantum chemistry to overcome challenges presented by the two main families of basis sets: Gaussian atomic orbitals and plane waves. In addition to their numerical advantages (high precision, locality, fast algorithms for operator application, linear scaling with respect to system size, to mention a few), they provide a framework that narrows the gap between the theoretical formalism of the fundamental equations and the practical implementation in a working code. This realization led us to the development of the Python library called VAMPyR (Very Accurate Multiresolution Python Routines). VAMPyR encodes the binding to a C++ library for multiwavelet calculations (algebra and integral and differential operator application) and exposes the required functionality to write a simple Python code to solve, among others, the Hartree-Fock equations, the generalized Poisson equation, the Dirac equation, and the time-dependent Schrödinger equation up to any predefined precision. In this study, we will outline the main features of multiresolution analysis using multiwavelets and we will describe the design of the code. A few illustrative examples will show the code capabilities and its interoperability with other software platforms.

Modelling of vertical displacement events in tokamaks: status and challenges ahead

In this paper, we revisit the physics of mitigated and unmitigated vertical displacement events (VDEs) and present a summary of present modelling efforts and code capabilities. While 3D MHD simulations of VDEs for AUG and JET are now approaching realistic plasma parameters (e.g. resistivity) and getting closer to experimental observations (e.g. CQ times and vessel forces), the time scales of ITER VDEs (∼500 ms) are still out of computational reach. Therefore, re-scaling of plasma parameters, model simplifications or demanding matrix pre-conditioning techniques are required. We describe such techniques and compare AUG, JET and ITER unmitigated VDE simulations in terms of the dynamics of the CQ and total vacuum vessel forces. In JET simulations, the safety factor (q 95) falls to unity during the current quench, which destabilizes a 1/1 kink mode. On the other hand, in AUG and ITER simulations, MHD activity is more effective preventing the drop of q 95, leading to comparatively smaller forces in these devices. We will also discuss the applicability of axisymmetric plasma simulations and their success on simulating mitigated disruptions. Finally we review the remaining modelling challenges and future plans for unmitigated disruptions. For example, MHD codes need to improve their scrape-off-layer modelling, such as including the limitation of the halo current to the ion saturation current. Although crucial, this remains numerically challenging even for axisymmetric simulations.

Temperature feedback reactivity analysis for LEU-Fuelled SLOWPOKE-2 research reactor using DRAGON5 and DONJON5 codes

The purpose of this study is to provide a new deterministic model for the SLOWPOKE-2 nuclear research reactor at École Polytechnique de Montréal (EPM) with LEU (Low Enriched Uranium) core. Using the latest release of the code system DRAGON5 and DONJON5 and the cross-section data library ENDFB.VII rel.1 evaluation, the developed model is applied to simulate the neutronic behavior of the SLOWPOKE-2 research reactor. We studied the separate temperature effects of the main components of the core (i.e., fuel, coolant/moderator, beryllium reflector, and water reflector). The contribution of different physical phenomena to the RTC was assessed. The temperature reactivity feedback calculated using the deterministic approach based on the DRAGON5 and DONJON5 code system using the ENDF/B-VII.1 evaluated nuclear data library produced in the WIMD-D4 format is in good agreement. Therefore, this work proves the capability of DRAGON5 and DONJON5 codes, normally used for power reactors, to reliably simulate a low-power research reactor.

Toward plasma drifts in EMC3: Implementation of gradient, divergence, and particle tracing schemes

AbstractThis paper presents a first implementation of gradient, divergence, and particle tracing schemes for the EMC3 code, a stochastic 3D plasma fluid code widely employed for edge plasma and impurity transport modeling in tokamaks and stellarators. These schemes are essential to accommodate plasma drift computations, which are currently absent in the code. Plasma drifts have been recognized to significantly influence transport of particles and energy, and their inclusion in future code upgrades will substantially enhance the code's predictive capabilities. For gradient and divergence calculations, we introduce a second‐order least‐squares gradient scheme. We confirm the second‐order convergence properties and assess the accuracy of several analytical test cases in the presence of synthetic noise. In the second part of this paper, we employ the validated gradient scheme in a fourth‐order Runge–Kutta particle tracing scheme to trace a particle through a generic drift velocity field. The impact of synthetic noise on the scheme's performance is investigated by evaluating various error metrics. We find that the implemented schemes function as intended and exhibit sufficient accuracy to enable drift computations.

A methodology to quantify effects of constitutive equations on safety analysis using integral effect test data

To improve the predictive capability of a nuclear thermal hydraulic safety analysis code by developing a better constitutive equation for individual phenomenon has been the general research direction until now. This paper proposes a new method to directly use complex experimental data obtained from integral effect test (IET) to improve constitutive models holistically and simultaneously. The method relies on the sensitivity of a simulation result of IET data to the multiple constitutive equations utilized during the simulation, and the sensitivity of individual model determines the direction of modification for the constitutive model. To develop a robust and generalized method, a clustering algorithm using an artificial neural network, sample space size determination using non-parametric statistics, and sampling method of Latin hypercube sampling are used in a combined manner. The value of the proposed methodology is demonstrated by applying the method to the ATLAS DSP-05 IET experiment. A sensitivity of each observation parameter to the constitutive models is analyzed. The new methodology suggested in the study can be used to improve the code prediction results of complex IET data by identifying the direction for constitutive equations to be modified.

Development of Code Evaluation System based on Abstract Syntax Tree

Analyzing and evaluating student-generated code poses a big headache for programming education. Code evaluation is a delicate task requiring accuracy, efficiency, and error-checking. This paper considers one of the many useful tools in code evaluation. It's Abstract Syntax Trees (AST). AST is a robust tool for reading, filtering, and weighing student code. It is built from tree regular expressions for common programming patterns. This paper considers, firstly, integrating AST into code evaluation projects. Secondly and most importantly to the present implementation work is that Python programming language provides excellent compatibility for implementing such a program. Taking advantage of Python's feature that allows the inputting of code as a string, AST records and tracks everything about the user's own source. With AST being integrated into platforms for education, how to evaluate student code has been completely altered; as sites such as LeetCode and HackerRank testify. This paper presents an accurate, efficient and error-aware approach to code evaluation by improving on educational websites incorporating AST. Adapting well to the dynamics of programming education, this elaborate assessment system will provide students with truthful assessments and profound feedback on their coding capabilities. This article shows how AST-based evaluation has revolutionized the way programming is taught, and thoroughly explores its role in evaluating code.

Extension and Validation of the Turbomachinery Capabilities of SU2 Open Source Computational Fluid Dynamic Code

Abstract Computational Fluid Dynamic (CFD) tools have revolutionized the way to design engineering systems, but most established codes are proprietary and closed-source, making it difficult, if not impossible, to modify, debug, or add new features to the code. To provide a freely available open-source CFD code for turbomachinery aerodynamics and aeroelasticity, this paper enhances the turbomachinery capabilities of the open-source SU2 code and demonstrates its capabilities of single-passage steady simulation, full-annulus unsteady simulation, and aeroelasticity analysis in two high-speed compressors, namely NASA Stage 35 and TUDa-GLR-OpenStage, and a linear cascade SC1. For the single-passage steady simulation of NASA Stage 35, the SU2 results are validated against the measured data and verified against the commercial solver ansys cfx, and the performance characteristics results are in reasonably good agreement with each other. For the single-passage steady simulation of TUDa-GLR-OpenStage, grid and turbulence model sensitivity studies are performed and results are validated against the measured data, and SU2 can predict both the performance characteristics and the radial profiles with sufficient accuracy. For the full-annulus unsteady simulation of NASA Stage 35, it is demonstrated that SU2 can predict the propagation of inlet distortion equally well as ansys cfx. For the linear cascade, SU2 can predict the unsteady pressure and aerodynamic damping coefficient accurately. The presented results demonstrate the turbomachinery aerodynamics and aeroelasticity capabilities of SU2. The major modifications of SU2 made in this work will be shared with the code maintainer and the community in the future.

TRIPOLI-4® calculations of neutron multiplicity counting rates of 3He array detectors and verification tests of an automatic MCNP-to-TRIPOLI conversion tool for recent ICSBEP subcritical experiments

TRIPOLI-4® is a general-purpose Monte Carlo radiation transport code developed at CEA Paris-Saclay center. It uses continuousenergy nuclear data to simulate neutron transport for diverse nuclear engineering fields. Neutron multiplication calculations of subcritical systems are important for application areas including criticality safety, reactor ex-core monitoring, and non-proliferation of nuclear materials. Subcritical experiments were performed by the LANL teams to improve subcritical simulation capabilities of MCNP code and to validate 3He based array detectors. Three of these experimental series based on Ni, W, and Cu reflected Pu spheres and related MCNP calculations were published on 2020 ICSBEP handbook. New automation conversion tool of MCNP geometries to TRIPOLI-4® ones has been available. In this study, the traditional manual modelling of above Pu-W and Pu-Cu cases (17 configurations including Cu and polyethylene reflectors) was first prepared. The MCNP/TRIPOLI-4® converted ones were secondly set for Pu-Cu cases. Finally the singles counting rate R1 (cts/s) in a single NPOD detector for Pu-W cases and in two NoMAD detectors for Pu-Cu cases were calculated. Generally, a good agreement of R1 was obtained between the TRIPOLI-4® calculations and the ICSBEP reported results. When using the polyethylene reflector layers in some Pu-Cu experiments, a difference of 5 to 16 % for R1 was observed between TRIPOLI-4 (Converted) results and the ICSBEP measured ones.

TURBULENCE MODELING OF SHOCK BOUNDARY LAYER INTERACTION IN HYPERSONIC FLOW

Computational fluid dynamics (CFD) simulations of shockwave turbulent boundary layer interactions using different turbulence modeling including Reynolds-averaged Navier-Stokes (RANS) with different closures (Menter's <i>k</i>-ω-SST, and Spalart-Allmaras) have been investigated. The objective of the study is to assess the capability of current CFD codes, Ansys Fluent and STARCCM, to model hypersonic flow over a large hollow cylinder flare for Mach 6 with Re<sub>∞</sub> = 5.33 × 10<sup>7</sup> The results of heat transfer and pressure data over the surface are presented for two-dimensional, axisymmetric, and three-dimensional RANS models using experimental data of LENS II high Reynolds number shock/Ludweig tunnel at the CUBRC center. Effects of properties of real gas, perfect gas, and different types of mesh have been considered for the assessment.

New dimension-independent upper bounds on linear insdel codes

To determine the insdel distances of linear codes is a very challenging problem. The half-Singleton bound on the insdel distances of linear codes due to Cheng-Guruswami-Haeupler-Li is a basic upper bound on the insertion-deletion error-correcting capabilities of linear codes. In this paper we give several new coordinate ordering-free and coordinate ordering-depending upper bounds for the insdel distances of linear codes. These upper bounds do not depend on dimensions of linear codes and only depend on the formations of codewords. It is shown that for many natural well-known linear codes including binary simplex codes, Kasami codes, many linear binary codes with few non-zero weights and some algebraic geometry codes, the new coordinate ordering-free upper bounds on their insdel distances are strictly smaller than the half-Singleton bound and the direct upper bound. On the other hand for many linear binary codes, the ordering-depending upper bound on their insdel distance is 2. We also give ordering-depending upper bounds on the insdel distances of some linear ternary codes with few non-zero weights and some binary and ternary algebraic geometry codes.

Optimization of multicomponent isotopes separation cascades parameters using improved grey wolf optimizer algorithm

The number of variables and design parameters in the multicomponent isotope separation cascades is considerable, and it is highly challenging to choose the best arrangement by obtaining the minimum interstage flow rate. Therefore, it is very important to develop a computational tool with high capability for calculating the cascade optimal parameters. The Improved Grey Wolf Algorithm, IGWO, is used in this study to develop an efficient code called the Isotopic Separation Real Code (ISRC-IGWO), which calculates the optimum parameters in the cascade for the separation of multicomponent mixtures. Investigations have been conducted in 4 separate tests to demonstrate this code's capability for computing the parameters with values close to the optimal conditions (in convergence to the near-optimal cascade). These evaluations have been carried out for both square and taper cascades, and different objective functions have been included in all tests. The findings show that ISRC-IGWO results are in agreement with optimal parameters calculation using other existing methods and IGWO is able to calculate cascade optimal parameters.

Scenario optimization for the tokamak ramp-down phase in RAPTOR: Part A. Analysis and model validation on ASDEX Upgrade

We discuss how the combination of experimental observations and rapid modeling has enabled to improve understanding of the tokamak ramp-down phase in ASDEX Upgrade. A series of dedicated experiments has been performed, to disentangle the effect of individual actuators like plasma current, auxiliary heating and plasma shaping. Optimized discharge termination strategies with increased margin with respect to radiative and vertical stability limits are proposed and tested in experiment. Radiative collapse of the edge Te profile after the HL back-transition is avoided by initially maintaining auxiliary heating during L-mode, showing beneficial effects even after the auxiliary heating is turned off. The capability of the RAPTOR code to model the time evolution of the internal inductance has been validated, including the effect of a change in the Ip ramp-down rate and the HL transition timing. The reduction of caused by rapid compression of the plasma cross-section has been quantitatively recovered in simulations. Successful modeling of the time evolution is essential to optimize ramp-down scenarios for future fusion reactors, for which vertical stability and power balance control will be more challenging.

The muphyII code: Multiphysics plasma simulation on large HPC systems

Collisionless astrophysical and space plasmas cover regions that typically display a separation of scales that exceeds any code's capabilities. To help address this problem, the muphyII code utilizes a hierarchy of models with different inherent scales, unified in an adaptive framework that allows stand-alone use of models as well as a model-based dynamic and adaptive domain decomposition. This requires ensuring excellent conservation properties, careful treatment of inner-domain model boundaries for interface coupling, and robust time-stepping algorithms, especially with the use of electron subcycling. This multi-physics approach is implemented in the muphyII code, tested on different scenarios of space plasma magnetic reconnection, and evaluated against space probe data and higher-fidelity simulation results from literature. Adaptive model refinement is highlighted in particular, and a hybrid model with kinetic ions, pressure-tensor fluid electrons, and Maxwell fields is appraised.

A computer code for optimizing the neutronics model parameters based on results of reactor physics experiments

The paper describes in brief the functional capabilities of a computer code for optimizing the neutronics model parameters (neutron data, technological parameters, and their covariance matrices) based on results of reactor physics experiments using conditional nonlinear multi-parameter optimization algorithms. The code’s application scope includes adjustment of neutron constants, technological parameters and their covariance matrices based on integral measurement results, formulation of requiremen117198ts with respect to the neutron data uncertainties for achieving the target accuracies in calculation of the reactor functionals, and estimation of the reactor performance prediction accuracy, as well as the informativity and similarity metrics of reactor physics experiments with respect to each other and in relation to the target reactor system. The paper also considers some examples of using the code to refine the neutronics models of nuclear reactor and fuel cycle systems based on results of reactor physics experiments.

Smart-Responsive HOF Heterostructures with Multiple Spatial-Resolved Emission Modes toward Photonic Security Platform.

Luminescent hydrogen-bonded organic frameworks (HOFs) with the unique dynamics and versatile functional sites hold great potential application in information security, yet most of responsive HOFs focus on the single-component framework with restrained emission control, limiting further applications in advanced confidential information protection. Herein, the first smart-responsive HOF heterostructure with multiple spatial-resolved emission modes for covert photonic security platform is reported. The HOF heterostructures are prepared by integrating different HOFs into a single microwire based on a hydrogen-bond-assisted epitaxial growth method. The distinct responsive behaviors of HOFs permit the heterostructure to simultaneously display the thermochromism via the framework transformation and the acidichromism via the protonation effect, thus generating multiple emission modes. The dual stimuli-controlled spatial-resolved emission modes constitute the fingerprint of a heterostructure, and enable the establishment of the smart-responsive photonic barcode with multiple convert states, which further demonstrate the dynamic coding capability and enhanced security in anticounterfeiting label applications. These results offer a promising route to design function-oriented smart responsive HOF microdevices toward advanced anticounterfeiting applications.

Identification of the protein coding capability of coronavirus defective viral genomes by mass spectrometry

During coronavirus infection, in addition to the well-known coronavirus genomes and subgenomic mRNAs, an abundance of defective viral genomes (DVGs) can also be synthesized. In this study, we aimed to examine whether DVGs can encode proteins in infected cells. Nanopore direct RNA sequencing and liquid chromatography-tandem mass spectrometry (LC–MS/MS) analysis were employed. With the protein databases generated by nanopore direct RNA sequencing and the cell lysates derived from the RNA–protein pull-down assay, six DVG-encoded proteins were identified by LC–MS/MS based on the featured fusion peptides caused by recombination during DVG synthesis. The results suggest that the coronavirus DVGs have the capability to encode proteins. Consequently, future studies determining the biological function of DVG-encoded proteins may contribute to the understanding of their roles in coronavirus pathogenesis and the development of antiviral strategies.

Quantum color image watermarking scheme based on quantum error correction coding * *This work was supported by the Open Fund of Advanced Cryptography and System Security Key Laboratory of Sichuan Province (Grant No. SKLACSS–202208), the Science and Technology Research Program of Chongqing Municipal Education Commission (Grant No. KJZD-M202000501) and National Natural Science Foundation of China (No. 61772295).

Quantum image processing, which merges classical image processing techniques with quantum computing, provides exceptional storage capacity and unparalleled parallel computing power. In this study, we present a quantum color image watermarking scheme that employs quantum error correction codes to address issues such as pixel loss and image distortion during watermark embedding and extraction. By utilizing the least significant bit method to embed the color values of the watermark image into those of the carrier image, we improve the scheme’s robustness. We also address the error correction capabilities of channel coding for phase-flip errors and follow the majority principle, resulting in more accurate extraction of the watermark image’s color and enhancing the watermarking scheme’s reliability and integrity. Our experimental simulations demonstrate that the proposed watermarking scheme boasts high security, strong robustness, and excellent concealment.

Development and Implementation of a Quick Response (QR) Code System to Streamline the Process for Fellows' Evaluation in the Pediatric Intensive Care Unit (PICU) and the Neonatal Intensive Care Unit (NICU) at a Large Academic Center.

Useful feedback and evaluation are critical to a medical trainee's development. While most academic physicians understand that giving feedback to learners is essential, many do not consider the components of feedback to be truly useful, and there are barriers to implementation. We sought to use a quick reader (QR) system to solicit feedback for trainees in two pediatric subspecialties (pediatric critical care and neonatal-perinatal medicine) at one institution to increase the quality and quantity of feedback received. New valuations were modified from the existing evaluations and imported into online systems with QR code capability. Each fellow was given a QR code linking to evaluations and encouraged to solicit feedback and evaluations in a variety of clinical settings and scenarios. Evaluation numbers and quality of evaluations were assessed and compared both pre- and post-intervention. There were increases in the number of evaluations completed for both the pediatric critical care fellows and the neonatal-perinatal medicine fellows. There was no overall change in the quality of written evaluations received. Satisfaction with the evaluation system improved for both faculty and fellows of both training programs. In our critical care units, we were successfully able to implement a QR code-driven evaluation for our fellows that improved access for the faculty and offered the ability of the learner to solicit evaluations, without compromising the number or quality of evaluations. What's new: Quick reader (QR) codes can be used by learners to solicit evaluations and feedback from faculty. They can increase the quantity of written evaluations received without affecting their quality.