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Journal articles on the topic 'Non-attractive set of initial approximations'

Author: Grafiati

Published: 3 June 2025

Last updated: 19 July 2025

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1

Anna, Malinova Angel Golev Anton Iliev* Nikolay Kyurkchiev. "SOME NOTES ON THE FAST ADAPTIVE NEURAL NETWORK SOLVERS." Global Journal of Engineering Science and Research Management 4, no. 10 (2017): 121–31. https://doi.org/10.5281/zenodo.1034497.

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With this paper, we discuss some important aspects related to the iterative solution of two classes of polynomials, nonlinear systems of equations, and the adapted to them – "FAST adaptive neural solver" (FANS). The crucial issue of choosing initial approximations (separation of unattractive networks of initial data) and the possibility of minimizing CPU–time with the use of existing FANS is discussed.

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Pelekh, Ya M., A. V. Kunynets, and R. Ya Pelekh. "TWO-SIDED METHODS FOR SOLVING INITIAL VALUE PROBLEM FOR NONLINEAR INTEGRO-DIFFERENTIAL EQUATIONS." Journal of Numerical and Applied Mathematics, no. 2 (2022): 116–21. http://dx.doi.org/10.17721/2706-9699.2022.2.13.

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Using the continued fractions and the method of constructing Runge-Kutta methods, numerical methods for solving the Cauchy problem for nonlinear Volterra non-linear integrodifferential equations are proposed. With appropriate values of the parameters, one can obtain an approximation to the exact solution of the first and second order of accuracy. We found a set of parameters for which we obtain two-sided calculation formulas, which at each step of integration allow to obtain the upper and lower approximations of the exact solution.

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Wang, Jinghua, and Hui Zhang. "Existence and decay rates of smooth solutions for a non-uniformly parabolic equation." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 132, no. 6 (2002): 1477–91. http://dx.doi.org/10.1017/s0308210500002213.

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We obtain the existence and decay rates of the classical solution to the initial-value problem of a non-uniformly parabolic equation. Our method is to set up two equivalent sequences of the successive approximations. One converges to a weak solution of the initial-value problem; the other shows that the weak solution is the classical solution for t > 0. Moreover, we show how bounds of the derivatives to the classical solution depend explicitly on the interval with compact support in (0, ∞). Then we study decay rates of this classical solution.

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Hayes, Brian, and Michael Shearer. "Undercompressive shocks and Riemann problems for scalar conservation laws with non-convex fluxes." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 129, no. 4 (1999): 733–54. http://dx.doi.org/10.1017/s0308210500013111.

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The Riemann initial value problem is studied for scalar conservation laws whose fluxes have a single inflection point. For a regularization consisting of balanced diffusive and dispersive terms, the travelling wave criterion is used to select admissible shocks. In some cases, the Riemann problem solution contains an undercompressive shock. The analysis is illustrated by exploring parameter space for the Buckley–Leverett flux. The boundary of the set of parameters for which there is a physical solution of the Riemann problem for all data is computed. Within the region of acceptable parameters,

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Guseva, S. R., and D. N. Ibragimov. "A priori estimation of the minimal stabilization time for linear discrete-time systems with bounded control based on the apparatus of eigensets." Modelling and Data Analysis 15, no. 1 (2025): 110–32. https://doi.org/10.17759/mda.2025150106.

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<p>A linear system with discrete time and bounded control is considered. It is assumed that the system matrix is non-singular and diagonalizable, and the set of admissible control values is convex and compact. For a given system, the time-optimization problem is studied. In particular, it is required to construct a priori estimates of the optimal value of the minimal time as a function of the initial state and system parameters that do not require an exact construction of the class of null-controllable sets. To solve the problem, an apparatus of eigensets of a linear transformation is de

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Trębicki, Grzegorz. "Merits of Fantastic Literature: A Proposal for Theoretical Framework." Literatura i Kultura Popularna 28 (October 6, 2022): 107–16. http://dx.doi.org/10.19195/0867-7441.28.8.

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The paper attempts to set ground for a comprehensive debate on the merits of non-mimetic (fantastic) literature, tentatively proposing a system of four basic merits — the entertaining/fabulative, the emotional-cognitive, the speculative/extrapolative, and the aesthetic. These merits can also be alternatively viewed as narrative functions, precisely defined presuppositions, agreements between the implied reader and writer as to what literary gratifications are to be expected by the reader from the reading experience. They constitute structural dominants which are well manifested in the texts th

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Shevchenko, I. I. "Using sequential particle methods and non-parametric distributions in bayesian evaluations of abundance and catch at age time series." Problems of Fisheries 24, no. 1 (2023): 99–116. http://dx.doi.org/10.36038/0234-2774-2023-24-1-99-116.

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We describe an approach to analyzing time series for two variables connected through the state model with abundance and catch data sets and cohort and catch equations as an example. First, we create a deterministic model with parameters that maximizes the closeness of given data and data generated by a model. Then, we obtain cohort stochastic models using the difference between initial and modeled data. They are represented as hidden Bayesian models with abundances as states and catches as observations. Using these models, one can evaluate posterior densities and calculate averages, deviations

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Almgren, A., R. Camassa, and R. Tiron. "Shear instability of internal solitary waves in Euler fluids with thin pycnoclines." Journal of Fluid Mechanics 710 (August 29, 2012): 324–61. http://dx.doi.org/10.1017/jfm.2012.366.

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AbstractThe stability with respect to initial condition perturbations of solitary travelling-wave solutions of the Euler equations for continuously, stably stratified, near two-layer fluids is examined numerically and analytically for a set of parameters of relevance for laboratory experiments. Numerical travelling-wave solutions of the Dubreil–Jacotin–Long equation are first obtained with a variant of Turkington, Eyland and Wang’s iterative code by testing convergence on the equation’s residual. In this way, stationary solutions with very thin pycnoclines (and small Richardson numbers) approa

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Verykokou, Styliani, and Charalabos Ioannidis. "EXTERIOR ORIENTATION ESTIMATION OF OBLIQUE AERIAL IMAGERY USING VANISHING POINTS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 123–30. http://dx.doi.org/10.5194/isprs-archives-xli-b3-123-2016.

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In this paper, a methodology for the calculation of rough exterior orientation (EO) parameters of multiple large-scale overlapping oblique aerial images, in the case that GPS/INS information is not available (e.g., for old datasets), is presented. It consists of five main steps; (a) the determination of the overlapping image pairs and the single image in which four ground control points have to be measured; (b) the computation of the transformation parameters from every image to the coordinate reference system; (c) the rough estimation of the camera interior orientation parameters; (d) the est

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Verykokou, Styliani, and Charalabos Ioannidis. "EXTERIOR ORIENTATION ESTIMATION OF OBLIQUE AERIAL IMAGERY USING VANISHING POINTS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 123–30. http://dx.doi.org/10.5194/isprsarchives-xli-b3-123-2016.

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In this paper, a methodology for the calculation of rough exterior orientation (EO) parameters of multiple large-scale overlapping oblique aerial images, in the case that GPS/INS information is not available (e.g., for old datasets), is presented. It consists of five main steps; (a) the determination of the overlapping image pairs and the single image in which four ground control points have to be measured; (b) the computation of the transformation parameters from every image to the coordinate reference system; (c) the rough estimation of the camera interior orientation parameters; (d) the est

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Palmer, Michael H., and John A. Blair-Fish. "Halogen Nuclear Quadrupole Coupling Constants in Non-axially symmetric Molecules; Ab initio Calculations, which Include Correlation, Compared with Experiment." Zeitschrift für Naturforschung A 53, no. 6-7 (1998): 370–82. http://dx.doi.org/10.1515/zna-1998-6-718.

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Abstract Ab initio determination of the electric field gradient (EFG) tensors at halogen and other centres ena-bled determination of the nuclear quadrupole coupling constants (NQCC) for a diverse set of C2v , C3v and other symmetry molecules of general formula MH2X2 and MHX3 , where the halogen atoms (X) are Cl, Br and I, and the heavy central atoms (M) are C and Si. The study presents results at a standardised level of calculation, triple-zeta in the valence space plus polarisation functions (TZVP) for the equilib-rium geometry stage; all-electron MP2 correlation is included in all these stud

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Shved, A. V., Ye O. Davydenko, and H. V. Horban. "INTELLECTUAL SUPPORT OF THE PROCESSES OF SEARCHING AND EXTRACTION OF PRECEDENTS IN CASE-BASED REASONING APPROACH." Radio Electronics, Computer Science, Control, no. 3 (November 3, 2024): 107. http://dx.doi.org/10.15588/1607-3274-2024-3-10.

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Context. The situational approach is based on the real-time decision-making methods for solving current problem situation. An effective tool for implementing the concept of a situational approach is an experience-based technique that widely known as сasebased reasoning approach. Reasoning by precedents allows solving new (latest) problems using knowledge and accumulated experience of previously solved problems. Since cases (precedents) describing a scenario for solving a certain problem situation are stored in the case library, their search and retrieval directly determine the system response

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Prasertpong, Rukchart. "Roughness of soft sets and fuzzy sets in semigroups based on set-valued picture hesitant fuzzy relations." AIMS Mathematics 7, no. 2 (2022): 2891–928. http://dx.doi.org/10.3934/math.2022160.

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<abstract><p>In the philosophy of rough set theory, the methodologies of rough soft sets and rough fuzzy sets have been being examined to be efficient mathematical tools to deal with unpredictability. The basic of approximations in rough set theory is based on equivalence relations. In the aftermath, such theory is extended by arbitrary binary relations and fuzzy relations for more wide approximation spaces. In recent years, the notion of picture hesitant fuzzy relations by Mathew et al. can be considered as a novel extension of fuzzy relations. Then this paper proposes extended ap

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Bertoli, Wesley, Ricardo P. Oliveira, and Jorge A. Achcar. "A New Semiparametric Regression Framework for Analyzing Non-Linear Data." Analytics 1, no. 1 (2022): 15–26. http://dx.doi.org/10.3390/analytics1010002.

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This work introduces a straightforward framework for semiparametric non-linear models as an alternative to existing non-linear parametric models, whose interpretation primarily depends on biological or physical aspects that are not always available in every practical situation. The proposed methodology does not require intensive numerical methods to obtain estimates in non-linear contexts, which is attractive as such algorithms’ convergence strongly depends on assigning good initial values. Moreover, the proposed structure can be compared with standard polynomial approximations often used for

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Zhang, Shuwei, Houpu Yang, Jin Zhao, and Shu Wang. "Abstract PO5-07-05: Deep learning can diagnose axillary lymph node metastases on optical virtual histologic images in breast cancer patients during surgery." Cancer Research 84, no. 9_Supplement (2024): PO5–07–05—PO5–07–05. http://dx.doi.org/10.1158/1538-7445.sabcs23-po5-07-05.

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Abstract Background: Reliable identification of axillary lymph node (ALN) involvement in patients with breast cancer allows for definitive axillary dissection at the time of the initial surgery, thus avoiding the need for a separate axillary surgery. However, conventional intraoperative ALN diagnostic methods are time-consuming and labor-intensive and can result in tissue destruction. Dynamic full field optical coherence tomography, also called dynamic cell imaging (DCI), has been developed and validated to offer rapid and label-free histologic approximations of metastatic and non-metastatic A

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Molinari, Irene, Roberto Tonini, Stefano Lorito, et al. "Fast evaluation of tsunami scenarios: uncertainty assessment for a Mediterranean Sea database." Natural Hazards and Earth System Sciences 16, no. 12 (2016): 2593–602. http://dx.doi.org/10.5194/nhess-16-2593-2016.

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Abstract. We present a database of pre-calculated tsunami waveforms for the entire Mediterranean Sea, obtained by numerical propagation of uniformly spaced Gaussian-shaped elementary sources for the sea level elevation. Based on any initial sea surface displacement, the database allows the fast calculation of full waveforms at the 50 m isobath offshore of coastal sites of interest by linear superposition. A computationally inexpensive procedure is set to estimate the coefficients for the linear superposition based on the potential energy of the initial elevation field. The elementary sources s

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Mezerdi, Mohamed Amine, and Nabil Khelfallah. "Stability and prevalence of McKean–Vlasov stochastic differential equations with non-Lipschitz coefficients." Random Operators and Stochastic Equations 29, no. 1 (2021): 67–78. http://dx.doi.org/10.1515/rose-2021-2053.

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Abstract We consider various approximation properties for systems driven by a McKean–Vlasov stochastic differential equations (MVSDEs) with continuous coefficients, for which pathwise uniqueness holds. We prove that the solution of such equations is stable with respect to small perturbation of initial conditions, parameters and driving processes. Moreover, the unique strong solutions may be constructed by an effective approximation procedure. Finally, we show that the set of bounded uniformly continuous coefficients for which the corresponding MVSDE have a unique strong solution is a set of se

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Jiang, Yulin, Qingmin Pu, and Wenbin Ding. "Reconstruction of Velocity Distribution in Partially-Filled Pipe Based on Non-Uniform Under-Sampling." Advances in Mathematical Physics 2020 (January 22, 2020): 1–8. http://dx.doi.org/10.1155/2020/6961286.

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In the process of research on the flow velocity distribution in a partially filled pipe, the under-sampling of measurement data often occurs. For the first time, this problem is solved by the improved non-uniform B-spline curve fitting approximation (NBSC) method. The main innovation of this method is to reconstruct the flow velocity distribution fitting curve with a small amount of non-uniform feature points containing flow velocity information. First, the curvature of a whole discrete sampled data is analyzed, then the weighted threshold is set, and the sampled points that satisfy the thresh

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Filipovich, O. V. "Two-element Selective Assembly with Non-linear Input-output Models Using Approximation." Intellekt. Sist. Proizv. 22, no. 2 (2024): 80–86. http://dx.doi.org/10.22213/2410-9304-2024-2-80-86.

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The process of single-parameter selective assembly of two elements is considered for the case of a nonlinear input-output modelapplication. Due to the objective complexity of determining the relations between the limit deviations and tolerances of input and output parameters, as well as the relative accuracy smallness due to the precision of the assembly, it is reasonable to represent the initial model in the form of a first-order polynomial of two variables. Linearisation is proposed to be carried out using a method of obtaining an approximating relation in the form of a Taylor series and by

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Obayomi, Adesoji, and Lukman Salaudeen. "A Non-Standard Finite Difference Schemes for the Solution of Stiff Initial Value Problems." International Journal of Development Mathematics (IJDM) 1, no. 3 (2024): 001–7. http://dx.doi.org/10.62054/ijdm/0103.01.

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In this study, we introduce a novel non-standard finite difference (NSFD) scheme designed to address the challenges posed by stiff initial value problems. Stiffness in differential equations often leads to numerical instability and requires specialized methods for stable and accurate solutions. A novel set of numerical schemes for solving stiff ordinary differential equations caused by the decay of radioactive substances developed. This paper demonstrates the power of normalization in the discretization function. We employed non-local approximation and renormalization of the denominator functi

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Pazis, Jason, and Ronald Parr. "Non-Parametric Approximate Linear Programming for MDPs." Proceedings of the AAAI Conference on Artificial Intelligence 25, no. 1 (2011): 459–64. http://dx.doi.org/10.1609/aaai.v25i1.7930.

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The Approximate Linear Programming (ALP) approach to value function approximation for MDPs is a parametric value function approximation method, in that it represents the value function as a linear combination of features which are chosen a priori. Choosing these features can be a difficult challenge in itself. One recent effort, Regularized Approximate Linear Programming (RALP), uses L1 regularization to address this issue by combining a large initial set of features with a regularization penalty that favors a smooth value function with few non-zero weights. Rather than using smoothness as a b

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GOHARA, KAZUTOSHI, HIROSHI SAKURAI, and SHOZO SATO. "EXPERIMENTAL VERIFICATION FOR FRACTAL TRANSITION USING A FORCED DAMPED OSCILLATOR." Fractals 08, no. 01 (2000): 67–72. http://dx.doi.org/10.1142/s0218348x00000081.

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A damped oscillator stochastically driven by temporal forces is experimentally investigated. The dynamics is characterized by a set Γ(C) of trajectories in a cylindrical space, where C is a set of initial states on the Poincaré section. Two sets, Γ(C) and C, are attractive and unique invariant fractal sets that approximately satisfy specific equations derived previously by the authors. The correlation dimension of the set C is in good agreement with the similarity dimension obtained for a strictly self-similar set constructed by contraction mappings while C is a self-affine set constructed by

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Alshehry, Azzh Saad, Roman Ullah, Nehad Ali Shah, Rasool Shah, and Kamsing Nonlaopon. "Implementation of Yang residual power series method to solve fractional non-linear systems." AIMS Mathematics 8, no. 4 (2023): 8294–309. http://dx.doi.org/10.3934/math.2023418.

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<abstract><p>In this study, we implemented the Yang residual power series (YRPS) methodology, a unique analytical treatment method, to estimate the solutions of a non-linear system of fractional partial differential equations. The RPS approach and the Yang transform are togethered in the YRPS method. The suggested approach to handle fractional systems is explained along with its application. With fewer calculations and greater accuracy, the limit idea is used to solve it in Yang space to produce the YRPS solution for the proposed systems. The benefit of the new method is that it re

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Романюк, Вадим Васильович. "Finite approximation of zero-sum games played in staircase-function continuous spaces." KPI Science News, no. 4 (February 14, 2022): 19–38. http://dx.doi.org/10.20535/kpisn.2021.4.242769.

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Background. There is a known method of approximating continuous zero-sum games, wherein an approximate solutionis considered acceptable if it changes minimally by changing the sampling step minimally. However, the method cannotbe applied straightforwardly to a zero-sum game played with staircase-function strategies. Besides, the independence ofthe player’s sampling step selection should be taken into account.Objective. The objective is to develop a method of finite approximation of zero-sum games played in staircase-functioncontinuous spaces by taking into account that the players are likely t

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Vadim Romanuke. "Equilibrium stacks for a non-cooperative game defined on a product of staircase-function continuous and finite strategy spaces." Statistics, Optimization & Information Computing 12, no. 1 (2023): 45–74. http://dx.doi.org/10.19139/soic-2310-5070-1356.

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A method of finite uniform approximation of 3-person games played with staircase-function strategies is presented. A continuous staircase 3-person game is approximated to a staircase trimatrix game by sampling the player’s pure strategy value set. The set is sampled uniformly so that the resulting staircase trimatrix game is cubic. An equilibrium of the staircase trimatrix game is obtained by stacking the equilibria of the subinterval trimatrix games, each defined on an interval where the pure strategy value is constant. The stack is an approximate solution to the initial staircase game. The (

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Richa, Munish Aggarwal, Harish Kumar, Ranju Mahajan, Navdeep Singh Arora, and Tarsem Singh Gill. "Relativistic ponderomotive self-focusing of quadruple Gaussian laser beam in cold quantum plasma." Laser and Particle Beams 36, no. 3 (2018): 353–58. http://dx.doi.org/10.1017/s026303461800023x.

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AbstractIn the present paper, we have investigated self-focusing of the quadruple Gaussian laser beam in underdense cold quantum plasma. The non-linearity chosen is associated with the relativistic mass effect that arises due to quiver motion of electron and electron density perturbation caused by ponderomotive force. The non-linearity modifies the plasma frequency in the dielectric function and hence the refractive index of the medium. The focusing/defocusing of the quadruple laser depends on the refractive index of the medium. We have set up non-linear differential equation that controls the

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Arabi naree, Somaye, and Maryam Mohammadi. "A new non-negative matrix factorization method to build a recommender system." Journal of Research in Science, Engineering and Technology 8, no. 2 (2020): 12–6. http://dx.doi.org/10.24200/jrset.vol8iss2pp12-6.

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The main aim of this paper is to apply non-negative matrix factorization to build a recommender system. In a recommender system there are a group of users that rate to a set of items. These ratings can be represented by a rating matrix. The main problem is to estimate the unknown ratings and then predict the interests of the users to the items which haven’t rated. The main innovation of this paper is to propose a new algorithm to compute matrix factorization in a way that the factorized matrixes would be a good approximation for the initial rating matrix and moreover would be a good source to

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Arabi naree, Somaye, and Maryam Mohammadi. "A New Non-Negative Matrix Factorization Method to Build a Recommender System." Journal of Management and Accounting Studies 8, no. 3 (2020): 56–61. http://dx.doi.org/10.24200/jmas.vol8iss3pp56-61.

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The main aim of this paper is to apply non-negative matrix factorization to build a recommender system. In a recommender system there are a group of users that rate to a set of items. These ratings can be represented by a rating matrix. The main problem is to estimate the unknown ratings and then predict the interests of the users to the items which haven’t rated. The main innovation of this paper is to propose a new algorithm to compute matrix factorization in a way that the factorized matrixes would be a good approximation for the initial rating matrix and moreover would be a good source to

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Alalawi, Huda, and Michael Strickland. "Far-from-equilibrium attractors for massive kinetic theory in the relaxation time approximation." EPJ Web of Conferences 296 (2024): 13004. http://dx.doi.org/10.1051/epjconf/202429613004.

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In this proceedings contribution, we summarize recent findings concerning the presence of early- and late-time attractors in non-conformal kinetic theory. We study the effects of varying both the initial momentum-space anisotropy and initialization times using an exact solution of the 0+1D boostinvariant Boltzmann equation with a mass- and temperature-dependent relaxation time. Our findings support the existence of a longitudinal pressure attractor, but they do not support the existence of distinct attractors for the bulk viscous and shear pressures. Considering a large set of integral moments

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Yang, Jaw-Yen, Bagus Putra Muljadi, Zhi-Hui Li, and Han-Xin Zhang. "A Direct Solver for Initial Value Problems of Rarefied Gas Flows of Arbitrary Statistics." Communications in Computational Physics 14, no. 1 (2013): 242–64. http://dx.doi.org/10.4208/cicp.290112.030812a.

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AbstractAn accurate and direct algorithm for solving the semiclassical Boltzmann equation with relaxation time approximation in phase space is presented for parallel treatment of rarefied gas flows of particles of three statistics. The discrete ordinate method is first applied to discretize the velocity space of the distribution function to render a set of scalar conservation laws with source term. The high order weighted essentially non-oscillatory scheme is then implemented to capture the time evolution of the discretized velocity distribution function in physical space and time. The method

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Blusseau, Samy, Bastien Ponchon, Santiago Velasco-Forero, Jesús Angulo, and Isabelle Bloch. "Approximating morphological operators with part-based representations learned by asymmetric auto-encoders." Mathematical Morphology - Theory and Applications 4, no. 1 (2020): 64–86. http://dx.doi.org/10.1515/mathm-2020-0102.

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AbstractThis paper addresses the issue of building a part-based representation of a dataset of images. More precisely, we look for a non-negative, sparse decomposition of the images on a reduced set of atoms, in order to unveil a morphological and explainable structure of the data. Additionally, we want this decomposition to be computed online for any new sample that is not part of the initial dataset. Therefore, our solution relies on a sparse, non-negative auto-encoder, where the encoder is deep (for accuracy) and the decoder shallow (for explainability). This method compares favorably to th

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Wyse, Rosemary F. G., and Bernard J. T. Jones. "A Model for the Sequence of Elliptical Galaxies." Symposium - International Astronomical Union 117 (1987): 367. http://dx.doi.org/10.1017/s0074180900150545.

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We present a simple model for the formation of elliptical galaxies, based on a binary clustering hierarchy of dark matter, the chemical enrichment of the gas at each level being controlled by supernovae. The initial conditions for the non-linear phases of galaxy formation are set by the post-recombination power spectrum of density fluctuations. We investigate two models for this power spectrum - the first is a straightforward power law, |δk|2 ∝ kn, and the second is Peeble's analytic approximation to the emergent spectrum in a universe dominated by cold dark matter. The normalisation is chosen

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Abbas, Umar Farouk, Abdulkadir Ahmed, and Usman Mukhtar. "BAYESIAN ESTIMATION OF FOUR PARAMETERS ADDITIVE CHEN-WEIBULL DISTRIBUTION." FUDMA JOURNAL OF SCIENCES 6, no. 1 (2022): 181–90. http://dx.doi.org/10.33003/fjs-2022-0601-891.

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Models with bathtub-shaped failure rate function have been widely accepted in the field of reliability and medicine and are particularly useful in reliability related decision making and cost analysis. In this study, the additive Chen-Weibull (ACW) distribution with increasing and bathtub-shaped failure rates function is studied using Bayesian and non-Bayesian approach using two real data set. The Bayes estimator were obtained by assuming non-informative prior (Half-Cauchy) under square error loss function (SELF), the Laplace Approximation and Monte Carlo Markov Chain (MCMC) techniques conduct

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Skinn, Brian. "(Invited) Estimation of the Onset of Mass Transfer Limitations in Pulsed Electrochemical Processes." ECS Meeting Abstracts MA2019-01, no. 20 (2019): 1100. http://dx.doi.org/10.1149/ma2019-01/20/1100.

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The contributions of the physical phenomena governing the distribution of current across an electrode in an electrochemical process are conventionally categorized as primary, secondary, and/or tertiary current distribution effects, which respectively embody geometric/ohmic, kinetic polarization, and concentration polarization effects. On virtually all non-trivial workpieces of interest to industrial electrochemical practice, it is important to be able to control the areas affected by the process; viz., preferentially adding or removing material to some regions over others. Two of the most sign

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Kapoor, Mamta, and Varun Joshi. "Numerical approximation of coupled 1D and 2D non-linear Burgers’ equations by employing Modified Quartic Hyperbolic B-spline Differential Quadrature Method." International Journal of Mechanics 15 (April 7, 2021): 37–55. http://dx.doi.org/10.46300/9104.2021.15.5.

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In this paper, the numerical solution of coupled 1D and coupled 2D Burgers' equation is provided with the appropriate initial and boundary conditions, by implementing "modified quartic Hyperbolic B-spline DQM". In present method, the required weighting coefficients are computed using modified quartic Hyperbolic B-spline as a basis function. These coupled 1D and coupled 2D Burgers' equations got transformed into the set of ordinary differential equations, tackled by SSPRK43 scheme. Efficiency of the scheme and exactness of the obtained numerical solutions is declared with the aid of 8 numerical

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Hafdallah, Abdelhak. "OPTIMAL CONTROL FOR A CONTROLLED ILL-POSED WAVE EQUATION WITHOUT REQUIRING THE SLATER HYPOTHESIS." Ural Mathematical Journal 6, no. 1 (2020): 84. http://dx.doi.org/10.15826/umj.2020.1.007.

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In this paper, we investigate the problem of optimal control for an ill-posed wave equation without using the extra hypothesis of Slater i.e. the set of admissible controls has a non-empty interior. Firstly, by a controllability approach, we make the ill-posed wave equation a well-posed equation with some incomplete data initial condition. The missing data requires us to use the no-regret control notion introduced by Lions to control distributed systems with ncomplete data. After approximating the no-regret control by a low-regret control sequence, we characterize the optimal control by a sing

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Gao, Guohua, Jeroen Vink, Fredrik Saaf, and Terence Wells. "Strategies to Enhance the Performance of Gaussian Mixture Model Fitting for Uncertainty Quantification." SPE Journal 27, no. 01 (2021): 329–48. http://dx.doi.org/10.2118/204008-pa.

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Summary When formulating history matching within the Bayesian framework, we may quantify the uncertainty of model parameters and production forecasts using conditional realizations sampled from the posterior probability density function (PDF). It is quite challenging to sample such a posterior PDF. Some methods [e.g., Markov chain Monte Carlo (MCMC)] are very expensive, whereas other methods are cheaper but may generate biased samples. In this paper, we propose an unconstrained Gaussian mixture model (GMM) fitting method to approximate the posterior PDF and investigate new strategies to furthe

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Kumar, Harish, Munish Aggarwal, Richa, Dinkar Sharma, Sumit Chandok, and Tarsem Singh Gill. "Significant enhancement in the propagation of cosh-Gaussian laser beam in a relativistic–ponderomotive plasma using ramp density profile." Laser and Particle Beams 36, no. 2 (2018): 179–85. http://dx.doi.org/10.1017/s0263034618000125.

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AbstractThe paper presents an investigation on self-focusing of cosh-Gaussian (ChG) laser beam in a relativistic–ponderomotive non-uniform plasma. It is observed numerically that the selection of decentered parameter and initial beam radius determines the focusing/defocusing of ChG laser beam. For given value of these parameters, the plasma density ramp of suitable length can avoid defocusing and enhance focusing effect significantly. Focusing length and extent of focusing may also be controlled by varying slope of the ramp density. A comparison with Gaussian beam has also been attempted for o

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Hartmeier, Michael, та Mathias Garny. "Minimal basis for exact time dependent kernels in cosmological perturbation theory and application to ΛCDM and w ₀ w_a CDM". Journal of Cosmology and Astroparticle Physics 2023, № 12 (2023): 027. http://dx.doi.org/10.1088/1475-7516/2023/12/027.

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Abstract We derive a minimal basis of kernels furnishing the perturbative expansion of the density contrast and velocity divergence in powers of the initial density field that is applicable to cosmological models with arbitrary expansion history, thereby relaxing the commonly adopted Einstein-de-Sitter (EdS) approximation. For this class of cosmological models, the non-linear kernels are at every order given by a sum of terms, each of which factorizes into a time-dependent growth factor and a wavenumber-dependent basis function. We show how to reduce the set of basis functions to a minimal amo

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Jones, Janet E., Philip Mellor, and Jesper Storm. "Limits on the Missing Mass in Dark Stellar Remnants." Symposium - International Astronomical Union 117 (1987): 411. http://dx.doi.org/10.1017/s0074180900150600.

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A set of comprehensive computer models for the chemical evolution of galaxies have been used to determine the limits on the amount of mass that could exist in the form of dark stellar remnants deriving from normal stellar evolutionary processes. In these models, the instantaneous recycling approximation is not assumed: stars are binned into 10 mass intervals, with different lifetimes, yields and remnant masses. The models were run using many different values for the IMF (including non-Salpeter and varying IMFs), star formation rates, yields, remnant masses, gas infall and outflow rates, primor

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Kehle, Christoph. "Diophantine approximation as Cosmic Censor for Kerr–AdS black holes." Inventiones mathematicae 227, no. 3 (2021): 1169–321. http://dx.doi.org/10.1007/s00222-021-01078-6.

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AbstractThe purpose of this paper is to show an unexpected connection between Diophantine approximation and the behavior of waves on black hole interiors with negative cosmological constant $$\Lambda <0$$ Λ < 0 and explore the consequences of this for the Strong Cosmic Censorship conjecture in general relativity. We study linear scalar perturbations $$\psi $$ ψ of Kerr–AdS solving $$\Box _g\psi -\frac{2}{3}\Lambda \psi =0$$ □ g ψ - 2 3 Λ ψ = 0 with reflecting boundary conditions imposed at infinity. Understanding the behavior of $$\psi $$ ψ at the Cauchy horizon corresponds to a linear a

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Manucharyan, G. E., W. Moon, F. Sévellec, A. J. Wells, J. Q. Zhong, and J. S. Wettlaufer. "Steady turbulent density currents on a slope in a rotating fluid." Journal of Fluid Mechanics 746 (April 2, 2014): 405–36. http://dx.doi.org/10.1017/jfm.2014.119.

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AbstractWe consider the dynamics of actively entraining turbulent density currents on a conical sloping surface in a rotating fluid. A theoretical plume model is developed to describe both axisymmetric flow and single-stream currents of finite angular extent. An analytical solution is derived for flow dominated by the initial buoyancy flux and with a constant entrainment ratio, which serves as an attractor for solutions with alternative initial conditions where the initial fluxes of mass and momentum are non-negligible. The solutions indicate that the downslope propagation of the current halts

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Demirović, Emir, Christian Schilling, and Anna Lukina. "In Search of Trees: Decision-Tree Policy Synthesis for Black-Box Systems via Search." Proceedings of the AAAI Conference on Artificial Intelligence 39, no. 26 (2025): 27250–57. https://doi.org/10.1609/aaai.v39i26.34934.

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Decision trees, owing to their interpretability, are attractive as control policies for (dynamical) systems. Unfortunately, constructing, or synthesising, such policies is a challenging task. Previous approaches do so by imitating a neural-network policy, approximating a tabular policy obtained via formal synthesis, employing reinforcement learning, or modelling the problem as a mixed-integer linear program. However, these works may require access to a hard-to-obtain accurate policy or a formal model of the environment (within reach of formal synthesis), and may not provide guarantees on the q

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Akishin, Pavel G., and Andrey A. Sapozhnikov. "The volume integral equation method in magnetostatic problem." Discrete and Continuous Models and Applied Computational Science 27, no. 1 (2019): 60–69. http://dx.doi.org/10.22363/2658-4670-2019-27-1-60-69.

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This article addresses the issues of volume integral equation method application to magnetic system calculations. The main advantage of this approach is that in this case finding the solution of equations is reduced to the area filled with ferromagnetic. The difficulty of applying the method is connected with kernel singularity of integral equations. For this reason in collocation method only piecewise constant approximation of unknown variables is used within the limits of fragmentation elements inside the famous package GFUN3D. As an alternative approach the points of observation can be repl

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Sadhak, Gautam* Mridul Jaggi Santosh Anand. "SOLVING TRANSPORTATION PROBLEMS USING THE BEST CANDIDATES METHOD." INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY 5, no. 9 (2016): 547–53. https://doi.org/10.5281/zenodo.154479.

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Problem statement: The optimization processes in mathematics, computer science and economics are solving effectively by choosing the best element from set of available alternatives elements. The most important and successful applications in the optimization refers to transportation problem (TP), that is a special class of the linear programming (LP) in the operation research (OR). Approach: The main objective of transportation problem solution methods is to minimize the cost or the time of transportation. Most of the currently used methods for solving transportation problems are trying to reac

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D’Amato, Elena, Constantino Carlos Reyes-Aldasoro, Arianna Consiglio, Gabriele D’Amato, Maria Felicia Faienza, and Marcella Zollino. "Detection of Pitt–Hopkins Syndrome Based on Morphological Facial Features." Applied Sciences 11, no. 24 (2021): 12086. http://dx.doi.org/10.3390/app112412086.

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This work describes a non-invasive, automated software framework to discriminate between individuals with a genetic disorder, Pitt–Hopkins syndrome (PTHS), and healthy individuals through the identification of morphological facial features. The input data consist of frontal facial photographs in which faces are located using histograms of oriented gradients feature descriptors. Pre-processing steps include color normalization and enhancement, scaling down, rotation, and cropping of pictures to produce a series of images of faces with consistent dimensions. Sixty-eight facial landmarks are auto

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Bazilevskiy, Mikhail Pavlovich. "Program for Constructing Quite Interpretable Elementary and Non-elementary Quasi-linear Regression Models." Proceedings of the Institute for System Programming of the RAS 35, no. 4 (2023): 129–44. http://dx.doi.org/10.15514/ispras-2023-35(4)-7.

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A quite interpretable linear regression satisfies the following conditions: the signs of its coefficients correspond to the meaningful meaning of the factors; multicollinearity is negligible; coefficients are significant; the quality of the model approximation is high. Previously, to construct such models, estimated using the ordinary least squares, the QInter-1 program was developed. In it, according to the given initial parameters, the mixed integer 0-1 linear programming task is automatically generated, as a result of which the most informative regressors are selected. The mathematical appa

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Azri, Hakim, Hafida Belbachir, and Fatiha Guerroudji Meddah. "Identifying Spam Activity on Public Facebook Pages." Journal of Computing and Information Technology 29, no. 3 (2022): 133–49. http://dx.doi.org/10.20532/cit.2021.1005221.

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Since their emergence, online social networks (OSNs) keep gaining popularity. However, many related problems have also arisen, such as the use of fake accounts for malicious activities. In this paper, we focus on identifying spammers among users that are active on public Facebook pages. We are specifically interested in identifying groups of spammers sharing similar URLs. For this purpose, we built an initial dataset based on all the content that has been posted upon feed posts on a set of public Facebook pages with high numbers of subscribers. We assumed that such public pages, with hundreds

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Ingel, Lev Kh. "On the onset of advective flow in a stratified medium induced by weak symmetry breaking of horizontal translations." Journal of Physics: Conference Series 2317, no. 1 (2022): 012001. http://dx.doi.org/10.1088/1742-6596/2317/1/012001.

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Abstract In this paper, we analytically study the mechanism of the onset of the liquid/gas flow in a non-isothermal stratified medium. The flow is induced by small spatial inhomogeneities of the exchange coefficients. In a statically stable stratified medium heated strictly from above, as is known, there is heat diffusion directed from top to bottom. We consider the system, which is slightly non-invariant with respect to translations along with horizontal directions. It may occur, for example, due to the dependence of the thermal conductivity coefficient on horizontal coordinates. In this case

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Hopmann, Ch, and C. Zimmermann. "Characterisation of the quasi-static material behaviour of thermoplastic elastomers (TPE) under consideration of temperature and stress state." Journal of Elastomers & Plastics 52, no. 3 (2019): 199–215. http://dx.doi.org/10.1177/0095244319835868.

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This article deals with the determination of the mechanical material behaviour of injection-moulded thermoplastic elastomers (TPE). For this purpose, the mechanical behaviour of TPE is investigated on basis of different materials (type and hardness) and process parameters with regard to the process-induced anisotropy. Based on these investigations, an almost isotropic material was selected for the investigations about the influence of temperature, stress state and load level. The results confirm that the hardness of the material and type of the processed material have an impact on the mechanic

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