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Entropy ◽  
2022 ◽  
Vol 24 (1) ◽  
pp. 104
Author(s):  
Marko Jercic ◽  
Ivan Jercic ◽  
Nikola Poljak

The properties of decays that take place during jet formation cannot be easily deduced from the final distribution of particles in a detector. In this work, we first simulate a system of particles with well-defined masses, decay channels, and decay probabilities. This presents the “true system” for which we want to reproduce the decay probability distributions. Assuming we only have the data that this system produces in the detector, we decided to employ an iterative method which uses a neural network as a classifier between events produced in the detector by the “true system” and some arbitrary “test system”. In the end, we compare the distributions obtained with the iterative method to the “true” distributions.


Aerospace ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 6
Author(s):  
Omkar Halbe ◽  
Manfred Hajek

This paper synthesizes a continuous, multivariable, finite-time-convergent, super-twisting attitude and rate controller for rotorcraft with the objective of providing desired handling qualities and robustness characteristics. A sliding manifold is defined in the system state space to represent ideal attitude and rate command response dynamics of relative degree one with respect to the command input. Subsequently, robust command tracking is achieved via the synthesis of a multivariable super-twisting flight controller, which renders the plant states convergent on to the defined sliding manifold in finite-time and in the presence of matched external disturbance input. To validate the efficacy of the controller, simulation results are presented based on a nonlinear, higher-order rotorcraft model operating in turbulence. True system convergence to the sliding manifold from an untrimmed state is shown to lie within the theoretically predicted finite-time convergence bound. Furthermore, simulations with a linear quadratic flight controller are also presented for performance comparison with the proposed super-twisting flight controller.


Author(s):  
Sungju Moon ◽  
Jong-Jin Baik

AbstractThe feasibility of using a (3N)-dimensional generalization of the Lorenz system in testing a traditional implementation of the ensemble Kalman filter is explored through numerical experiments. The generalization extends the Lorenz system, known as the Lorenz ’63 model, into a (3N)-dimensional nonlinear system for any positive integer N. Because the extension involves inclusion of additional wavenumber modes, raising the dimension allows the system to resolve smaller-scale motions, a unique characteristic of the present generalization that can be relevant to real modeling scenarios. Model imperfections are simulated by assuming a high-dimensional generalized Lorenz system as the true system and a generalized system of dimension less than or equal to the dimension of the true system as the model system. Different scenarios relevant to data assimilation practices are simulated by varying the dimensional-differences between the model and true systems, ensemble size, and observation frequency and accuracy. It is suggested that the present generalization of the Lorenz system is an interesting and flexible tool for evaluating the effectiveness of data assimilation methods and a meaningful addition to the portfolio of testbed systems that includes the Lorenz ’63 and ’96 models, especially considering its relationship with the Lorenz ’63 model. The results presented in this study can serve as useful benchmarks for testing other data assimilation methods besides the ensemble Kalman filter.


Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1580
Author(s):  
Junseok Lim ◽  
Keunhwa Lee ◽  
Seokjin Lee

In this paper, we propose a new calculation method for the regularization factor in sparse recursive least squares (SRLS) with l1-norm penalty. The proposed regularization factor requires no prior knowledge of the actual system impulse response, and it also reduces computational complexity by about half. In the simulation, we use Mean Square Deviation (MSD) to evaluate the performance of SRLS, using the proposed regularization factor. The simulation results demonstrate that SRLS using the proposed regularization factor calculation shows a difference of less than 2 dB in MSD from SRLS, using the conventional regularization factor with a true system impulse response. Therefore, it is confirmed that the performance of the proposed method is very similar to that of the existing method, even with half the computational complexity.


Author(s):  
Kevin W. Irick ◽  
Nima Fathi

Abstract Physics models — such as thermal, structural, and fluid models — of engineering systems often incorporate a geometric aspect such that the model resembles the shape of the true system that it represents. However, the physical domain of the model is only a geometric representation of the true system, where geometric features are often simplified for convenience in model construction and to avoid added computational expense to running simulations. The process of simplifying or neglecting different aspects of the system geometry is sometimes referred to as “defeaturing.” Typically, modelers will choose to remove small features from the system model, such as fillets, holes, and fasteners. This simplification process can introduce inherent error into the computational model.Asimilar event can even take place when a computational mesh is generated, where smooth, curved features are represented by jagged, sharp geometries. The geometric representation and feature fidelity in a model can play a significant role in a corresponding simulation’s computational solution. In this paper, a porous material system — represented by a single porous unit cell — is considered. The system of interest is a two-dimensional square cell with a centered circular pore, ranging in porosity from 1% to 78%. However, the circular pore was represented geometrically by a series of regular polygons with number of sides ranging from 3 to 100. The system response quantity under investigation was the dimensionless effective thermal conductivity, k*, of the porous unit cell. The results show significant change in the resulting k* value depending on the number of polygon sides used to represent the circular pore. In order to mitigate the convolution of discretization error with this type of model form error, a series of five systematically refined meshes was used for each pore representation. Using the finite element method (FEM), the heat equation was solved numerically across the porous unit cell domain. Code verification was performed using the Method of Manufactured Solutions (MMS) to assess the order of accuracy of the implemented FEM. Likewise, solution verification was performed to estimate the numerical uncertainty due to discretization in the problem of interest. Specifically, a modern grid convergence index (GCI) approach was employed to estimate the numerical uncertainty on the systematically refined meshes. The results of the analyses presented in this paper illustrate the importance of understanding the effects of geometric representation in engineering models and can help to predict some model form error introduced by the model geometry.


2021 ◽  
Vol 258 ◽  
pp. 10013
Author(s):  
Marina Vinogradova

This article deals with the implementation of interdisciplinary relations through the problems of applied nature of students studying in the specialty 23.05.04 Operation of railway doro on the example of the implementation of the discipline «Mathematics». The purpose of this article is to teach the student to solve problems of an applied nature that are of interest to the student. When using a subject-based learning system, interdisciplinary connections allow us to solve the existing contradictions between the disparate assimilation of knowledge and the need for their application, both holistic and complex, in the practical life of a person. As a result, knowledge becomes not only concrete, but also generalized, which gives students the opportunity to transfer this knowledge to new situations and apply it in practice. The article substantiates the need for interdisciplinary connections to reflect the integrity of nature in the content of educational material, to create a true system of knowledge and understanding of the world.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peter D. Larsen

AbstractThis paper considers Berkeley’s use of Plato in Siris. Berkeley’s engagement with ancient thinkers in Siris has been a source of puzzlement for many readers. In this paper I focus on Siris § 266. In particular, I consider why Berkeley says of the Platonists that they “distinguished the primary qualities in bodies from the secondary” and why, given his own well-known misgivings about the distinction, he characterizes this as part of a “notion of the true system of the world.” I argue that in Siris Berkeley accepts a distinctive form of corpuscularianism, and that he thinks a distinction between primary and secondary qualities follows from this. I further argue that in § 266, and elsewhere in Siris, Berkeley engages in a careful reading of Plato’s Timaeus, which he uses to bolster his defense of the compatibility between corpuscularianism and his immaterialist idealism.


2020 ◽  
Author(s):  
Jonas M B Haslbeck ◽  
Oisín Ryan

Idiographic modeling is rapidly gaining popularity and promises to tap into the within-person dynamics underlying psychological phenomena. To gain theoretical understanding of these dynamics, we need to make inferences from time series models about the underlying system. Such inferences are subject to two challenges: the time series models will arguably always be misspecified, which means that it is unclear how to make inferences to the underlying system; and second, the sampling frequency must be sufficient to capture the dynamics of interest. We discuss both problems with the following approach: we specify a toy model for emotion dynamics as the true system, generate time series data from it, and then try to recover that system with the most popular time series analysis tools. We show that making straightforward inferences from time series models about an underlying system is difficult. We also show that if the sampling frequency is insufficient, the dynamics of interest cannot be recovered. However, we also show that global characteristics of the system can be recovered reliably. We conclude by discussing the consequences of our findings for idiographic modeling and suggest to adopt a modeling methodology that goes beyond fitting time series models alone.


2020 ◽  
Vol 33 (6) ◽  
pp. 259-264
Author(s):  
Alan A. Monavvari ◽  
Lori Brady ◽  
Lisa Harper ◽  
Parisa Mehrfar

Although national spending on healthcare has progressed on an upward trend over several decades, issues regarding performance remain. Challenges such as access to specialist care and maternal and infant mortality rates contributed to Canada’s recent ranking of ninth among 11 Organisation for Economic Co-operation and Development countries for overall health system performance. Although disruptive transformation is required to resolve our chronic performance issues, effective change cannot be realized without addressing the foundational elements of patient-centred care, interprofessional care, and system integration. Inspired by examples of innovative disruption in other jurisdictions and industries, these three concepts are outlined as the core ingredients for healthcare transformation and describe how they currently function in a paradoxical manner—as self-contradictory statements which in reality are not executed to their true meaning. This article illustrates how improvements in health system performance are hinged to the need to rectify and fuse these three mutually inclusive and inseparable concepts.


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