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Scientific Visualization 2023年第2期15卷 125-133页

作者： Elistratov, S.A. Shirshov Institute of Oceanology of RAS Moscow Russia Ivannikov Institute for System Programming of RAS Moscow Russia

Hydrodynamical structure attending a flow can be hid and hardly to reveal. One of the methods to find them is to use mode decomposition (such as Proper orthogonal decomposition, POD). The method represents the field given as a series of spatial modes multiplied by corresponding temporal coefficients. In the article the method is discussed applyingly to a complex flow with a wave attractor structure. Attractor modes present structured vortex-like figure which cannot be claimed to be aleatory. As it turns out POD modes are not just a formal decomposition but have a physical origin: they are connected with instability cascade minor frequencies, as spectral investigation shows. Another consequence of that is that one of the collateral structure maximum can be visible. This proposition is proven as the structure is found to be visible in the flow itself. © 2023 National Research Nuclear University. All rights reserved.

关键词： Visualization

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Numerical and analytical models for prediction of the local scour under pipelines

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Journal of Hydrodynamics 2024年第6期36卷 1130-1141页

作者： Andrey Epikhin Igor Potapov Aleksandr Petrov Aleksandr Kukharskii Ivannikov Institute for System Programming of the RAS MoscowRussia Computing Center FEB RAS Khabarovsk680000Russia Ishlinsky Institute for Problems in Mechanics RAS MoscowRussia

This paper considers local scour around a pipeline under turbulent *** Navier-Stokes equations are solved with a shear stress turbulence *** original bed deformation equation based on an analytical sediment transport model is used to describe the changes in the bottom *** proposed sediment transport equation is based on Coulomb’s friction law for granular flow,Prandtl’s friction law for turbulent flow,and agrees with a large number of phenomenological formulas by other authors.A numerical algorithm for solving the mathematical model of bed surface erosion is implemented in *** simulations of the problem show that under the influence of turbulent flow generated at the pipeline streamline,a characteristic bottom wave of low steepness appears,the parameters of which asymptotically agree with the experimental *** on the analysis of experimental and numerical studies of the considered case,an assumption about the self-similar behavior of the bed surface evolution is *** on this assumption,a new method of constructing the self-similar dependence of the bed surface on time and space coordinates is *** the proposed approach,the average values of tangential bottom stresses are determined for a number of self-similar bottom surface shapes,and then the rates of change of bottom wave lengths and amplitudes are calculated using the proposed analytical model.A comparison with experimental data and numerical calculations shows that the solution error does not exceed a few percent and the computational time is reduced by up to 30 times.

关键词： Pipelines numerical simulation sediment transport scour hydrodynamics self-similar behavior OpenFOAM

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Methods of Visualisation for Flows with Internal Waves Attractors

Scientific Visualization

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Scientific Visualization 2021年第5期13卷 113-121页

作者： Ryazanov, D.A. Elistratov, S.A. Kraposhin, M.V. Ivannikov Institute for System Programming The RAS Russia Lomonosov Moscow State University Russia

Application of different approaches for visualization of hydrodynamic fields of internal waves is closely connected with the possibility of extracting important numerical characteristics of the flows. In this paper we describe methods of visualisation, which were shown to be very effective for the illustration of the internal wave attractors both for laboratory experiments and numerical simulations. On the other hand, some novel approaches for description of the wave flows with accumulation of energy are discussed. Methods of vortices identification show interesting properties of the wave flows, and may give an alternative for the estimation of the width of wave beams. At the same time, the limitations of the applicability of the described methods strongly depend on the space and time resolution of the available data, which is especially important in the areas of the internal wave beam reflection. © 2021 National Research Nuclear University. All rights reserved.

关键词： Open source software

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Neuron Coverage Maximization for Effective Test Set Construction with Respect to the Model

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Journal of Mathematical Sciences (United States) 2024年第2期285卷 189-200页

作者： Kushchuk, D. Ryndin, M. Ivannikov Institute for System Programming of the RAS Moscow Russian Federation

Real world data is not stationary and thus models must be monitored in production. One way to be sure in a model’s performance is regular testing. If the labels are not available, the task of minimizing the labeling cost can be formulated. In this work, we investigate and develop various ways to construct a minimum test set for a given trained model, in a fashion where the accuracy of the model calculated on the chosen subset is as close to the real one as possible. We focus on the white box scenario and propose a novel approach that uses neuron coverage as a observable functional to maximize in order to minimize the number of samples. We evaluate the proposed approach and compare it to Bayesian methods and stratification algorithms that are the main approaches to solve this task in literature. The developed method shows approximately the same level of performance but has a number of advantages over its competitors. It is deterministic, thus eliminating the dispersion of the results. Also, this method can give one a hint on the optimal budget. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.

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Realistic Adversarial Attacks on Object Detectors Using Generative Models

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Journal of Mathematical Sciences (United States) 2024年第2期285卷 245-254页

作者： Shelepneva, D. Arkhipenko, K. Ivannikov Institute for System Programming of the RAS Moscow Russian Federation

An important limitation of existing adversarial attacks on real-world object detectors lies in their threat model: adversarial patch-based methods often produce suspicious images while image generation approaches do not restrict the attacker’s capabilities of modifying the original scene. We design a threat model where the attacker modifies individual image segments and is required to produce realistic images. We also develop and evaluate a white-box attack that utilizes generative adversarial nets and diffusion models as a generator of malicious images. Our attack is able to produce high-fidelity images as measured by the Fréchet inception distance (FID) and reduces the mAP of Faster R-CNN model by over 0.2 on Cityscapes and COCO-Stuff datasets. A PyTorch implementation of our attack is available at https://***/DariaShel/gan-attack. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.

关键词： adversarial examples diffusion models generative adversarial networks object detectors

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Automatic verification of the text layer correctness in PDF documents

Automatic verification of the text layer correctness in PDF ...

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2024 ivannikov Memorial Workshop, IVMEM 2024

作者： Belyaeva, Oksana V. Golodkov, Aleksandr Bukhatov, Bekzat Programming of the RAS Ivannikov Institute for System Moscow Russia

ISBN: (纸本)9798331504663

PDF documents can contain incorrect textual layers due to low scanning quality, font embedding errors or other reasons. An incorrect text layer can significantly hamper automatic document processing and limit document parsing. To help tackle the problem, this work analyzed the causes of incorrect text layers (gibberish characters) and described a method to automatically extract text information by detecting the correct text layer of PDF files, using OCR and a PDF extractor. To determine the correctness/incorrectness of the text layer obtained from PDF extractors in the method, we trained a binary classifier on the generated *** carried out experiments and assessed the quality of various classification models for text correctness, tested the method on real data, thereby confirming the effectiveness of the developed approach. The obtained results can be useful for further development of methods for automatically checking textual layers and improving the quality of automatic processing PDF documents. © 2024 IEEE.

关键词： Automatic PDF text extraction Corrupted PDF Gibberish text detection Machine learning Reasons for text incorrectness Text classification

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Towards Symbolic Pointers Reasoning in Dynamic Symbolic Execution

Towards Symbolic Pointers Reasoning in Dynamic Symbolic Exec...

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2021 ivannikov Memorial Workshop, IVMEM 2021

作者： Kuts, Daniil Ivannikov Institute for System Programming RAS Moscow Russia

ISBN: (纸本)9781665423274

Dynamic symbolic execution is a widely used technique for automated software testing, designed for execution paths exploration and program errors detection. A hybrid approach has recently become widespread, when the main goal of symbolic execution is helping fuzzer increase program coverage. The more branches symbolic executor can invert, the more useful it is for fuzzer. A program control flow often depends on memory values, which are obtained by computing address indexes from user input. However, most DSE tools don't support such dependencies, so they miss some desired program branches. We implement symbolic addresses reasoning on memory reads in our dynamic symbolic execution tool Sydr. Possible memory access regions are determined by either analyzing memory address symbolic expressions, or binary searching with SMT-solver. We propose an enhanced linearization technique to model memory accesses. Different memory modeling methods are compared on the set of programs. Our evaluation shows that symbolic addresses handling allows to discover new symbolic branches and increase the program coverage. © 2021 IEEE.

关键词： Software testing

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Aerodynamic Analysis of Delta Wing Aircraft and Effect of the Propeller Using OpenFOAM

Aerodynamic Analysis of Delta Wing Aircraft and Effect of th...

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2023 ivannikov ISPras Open Conference, ISPras 2023

作者： Mkoyan, Ruslan Romanova, Daria Sargsyan, Sevak Epikhin, Andrey Russian-Armenian University Ivannikov Institute for System Programming of the Ras Center of Advanced Software Technologies Yerevan Armenia Ivannikov Institute for System Programming of the Ras Lomonosov Msu Moscow Russia Ivannikov Institute for System Programming of the Ras Moscow Russia

ISBN: (纸本)9798350349993

This paper presents a calculation of the aerodynamic characteristics of the ZOHD Alpha Strike UAV model, designed with a delta wing. The focus of the study is the overall layout of the aircraft and the influence of the propeller on its aerodynamic characteristics. The computational fluid dynamics tool OpenFOAM is used as an effective method to solve the complex aerodynamic problems inherent in this UAV model. Research is carried out in an incompressible flow, due to the low speeds inherent in such aircraft. A numerical methodology is proposed for quick evaluation of the aerodynamic performances of UAV models with a propeller. A simple dynamic model and flight data are presented. The calculation results are verified using a flight experiment. © 2023 IEEE.

关键词： Computational fluid dynamics

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Halocline Internal Wave Attractors Visualization

Scientific Visualization

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Scientific Visualization 2024年第50期16卷 82-94页

作者： Elistratov, Stepan A Shirshov Institute of Oceanology of RAS Russia B Ivannikov Institute for System Programming of RAS Russia C Sobolev Institute of Mathematics the Siberian Branch of the RAS Russia

The phenomenon of wave attractor, originating from ocean dynamics, in the last couple decades has become widely-studied both laboratorily and numerically. However, their discoveries in wild nature are still rare hence deepwater ones are out of technique, and attractor in smaller basins cannot form because of energy overinjection. In the current work we show that attractor may exist in shallower depths regardless the depth of the basin’s bottom. Basing on the peculiar dispersion relation typical for stratified fluid attractors can be"trapped" in a narrow halocline layer which may facilitate their detection in the nature. Additionally, we discuss the formed flow structure visualization problems. © 2024 National Research Nuclear University. All rights reserved.

关键词： Computational fluid dynamics

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Using Lingvodoc platform for researching genetic and areal semantic shifts: the case of Ob-Ugric basic vocabulary

Using Lingvodoc platform for researching genetic and areal s...

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2022 ivannikov Open Conference, ISPras 2022

作者： Normanskaya, Julia V. Institute of Linguistics Ras Ivannikov Institute for System Programming Ras Moscow Russia

ISBN: (纸本)9798350398533

Article analysis consists the list the significance of the main results that were obtained when analyzing the graph-phonetic features of the first Cyrillic books in the XIX century:*** first Cyrillic books allow us to see how the classification of dialects *** first Cyrillic books allow you to date the time of phonetic *** first Cyrillic books make it possible to verify the accuracy of transcription of extinct dialects completed by different *** first Cyrillic books made it possible to identify phenomena that persist in modern dialects and existed in the XIX century, but previously did not attract the systematic attention of *** first Cyrillic books make it possible to clarify the territory where speakers of some dialects had previously *** first Cyrillic books confirm the reconstruction of the *** books allow us to clarify the reconstruction of the *** first Cyrillic books allow us to establish who was the true creator of literary languages. © 2022 IEEE.

关键词： Semantics

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