scholarly journals Contextual movement models based on normalizing flows

2021 ◽  
Author(s):  
Samuel G. Fadel ◽  
Sebastian Mair ◽  
Ricardo da Silva Torres ◽  
Ulf Brefeld
Keyword(s):  
Computation Time ◽  
Point Of View ◽  
Spatiotemporal Data ◽  
Movement Model ◽  
Professional Soccer ◽  
Movement Models ◽  
Current Point ◽  
Interpretable Models ◽  
Physical Principles ◽  
A Current

AbstractMovement models predict positions of players (or objects in general) over time and are thus key to analyzing spatiotemporal data as it is often used in sports analytics. Existing movement models are either designed from physical principles or are entirely data-driven. However, the former suffers from oversimplifications to achieve feasible and interpretable models, while the latter relies on computationally costly, from a current point of view, nonparametric density estimations and require maintaining multiple estimators, each responsible for different types of movements (e.g., such as different velocities). In this paper, we propose a unified contextual probabilistic movement model based on normalizing flows. Our approach learns the desired densities by directly optimizing the likelihood and maintains only a single contextual model that can be conditioned on auxiliary variables. Training is simultaneously performed on all observed types of movements, resulting in an effective and efficient movement model. We empirically evaluate our approach on spatiotemporal data from professional soccer. Our findings show that our approach outperforms the state of the art while being orders of magnitude more efficient with respect to computation time and memory requirements.

On Drift Instabilities in a Collisionless Electron-Proton Plasma from the point of view of Energy Absorption of Resonant Particles

1963 ◽  
Vol 18 (4) ◽  
pp. 446-453 ◽  
Author(s):  
Asbjørn Kildal
Keyword(s):  
Energy Absorption ◽  
Constant Electric Field ◽  
Wave Length ◽  
Collisionless Plasma ◽  
Phase Region ◽  
Point Of View ◽  
Electrostatic Waves ◽  
Transverse Current ◽  
Special Cases ◽  
A Current

The present paper is essentially devoted to the study of instabilities of electrostatic waves in a current-carrying collisionless plasma. As the underlying physical cause of the instabilities is the same as that of the LANDAU damping in an electron plasma, a detailed analysis of the latter is first given. It is shown that the damping may be considered as being due to the fact that there are more electrons in the phase-region where energy is absorbed by the particles from the field than in the phase-region where energy is given up to the field.We then proceed to the evaluation of the energy absorption A of the resonant particles, first in the absence of an external magnet field, B0 , next when the wave is propagated under an arbitrary angle with respect to B0 . When A > 0, the wave is damped, and vice-versa. Without appeal to a dispersion equation, stability criteria can thus be found, dependent on the wave frequency and wave-vector. Next some special cases are investigated and compared with the results of other authors where such results exist.As a consequence of the fact that some ions and electrons, the resonant particles, experience a constant electric field, these particles also experience a constant drift transverse to both E and B0. This drift gives rise to a transverse current which is closely related to the damping or growing of the wave. An expression for this current, averaged over one wave-length is found.

scholarly journals The Regularized Weak Functional Matching Pursuit for linear inverse problems

2019 ◽  
Vol 27 (3) ◽  
pp. 317-340 ◽  
Author(s):  
Max Kontak ◽  
Volker Michel
Keyword(s):  
Inverse Problems ◽  
Matching Pursuit ◽  
A Priori ◽  
Computation Time ◽  
Point Of View ◽  
Computational Point ◽  
Linear Inverse Problems ◽  
Infinite Dimensional ◽  
Frame Condition ◽  
Ill Posed

Abstract In this work, we present the so-called Regularized Weak Functional Matching Pursuit (RWFMP) algorithm, which is a weak greedy algorithm for linear ill-posed inverse problems. In comparison to the Regularized Functional Matching Pursuit (RFMP), on which it is based, the RWFMP possesses an improved theoretical analysis including the guaranteed existence of the iterates, the convergence of the algorithm for inverse problems in infinite-dimensional Hilbert spaces, and a convergence rate, which is also valid for the particular case of the RFMP. Another improvement is the cancellation of the previously required and difficult to verify semi-frame condition. Furthermore, we provide an a-priori parameter choice rule for the RWFMP, which yields a convergent regularization. Finally, we will give a numerical example, which shows that the “weak” approach is also beneficial from the computational point of view. By applying an improved search strategy in the algorithm, which is motivated by the weak approach, we can save up to 90  of computation time in comparison to the RFMP, whereas the accuracy of the solution does not change as much.

scholarly journals A Responsive Paradigm for Technology Enhanced Learning (Tel) Integration Into Business Organizations

2014 ◽  
Vol 17 (2) ◽  
pp. 195-207
Author(s):  
Lina Kaminskienė ◽  
Elena Trepulė ◽  
Aušra Rutkienė ◽  
Gintaras Arbutavičius
Keyword(s):  
Qualitative Research ◽  
Literature Review ◽  
Point Of View ◽  
Technology Enhanced Learning ◽  
Business Organizations ◽  
Focus Group Interviews ◽  
Group Interviews ◽  
Enhanced Learning ◽  
A Current ◽  
Successful Technology

Abstract The purpose of this paper is to explore the main barriers and enablers for integrating technology enhanced learning (TEL) into a business organization based on a responsive paradigm. The study is based on a current literature review on challenges and learners’ needs for TEL and the preconditions for TEL curriculum integration into business organizations. The theoretical study is matched with a qualitative research on learners’ needs for TEL in two international business organizations from IT sector. Technology enhanced learning (TEL) is tackling different barriers for learning in organizations. However, to make it effective, specific technological and teaching solutions must be implemented. The research revealed that companies’ employees give preference to TEL than other forms of learning, and defined specific requirements for successful technology enhanced learning integration into business organisations. A theoretical literature review is followed by empirical findings of a qualitative research (focus group interviews) in two international IT companies. The findings of the research offer valuable insights for a responsive TEL integration into business organizations from the point of view of companies’ employees.

ADI-CRSTS: A New Method for the Moving Heat Sources — Application to a Train Pantograph Strip

2017 ◽  
Author(s):  
Nicolas Delcey ◽  
Philippe Baucour ◽  
Didier Chamagne ◽  
Geneviève Wimmer ◽  
Odile Bouger ◽  
...  
Keyword(s):  
Thermal Flux ◽  
Computation Time ◽  
Point Of View ◽  
Heat Sources ◽  
Physical Point ◽  
Alternating Direction Implicit ◽  
Alternating Direction ◽  
Refined Meshes ◽  
Physical Phenomena ◽  
Locally Refined Meshes

The pantograph strip interface involves many physical phenomena. Temperature evolution is one of them. This problem includes various thermal flux and sources. More specifically, due to the train motion, a moving zigzag heat source occurs. This paper deals with a thermal 2D Alternating Direction Implicit (ADI) numerical method for temperature estimations in the train pantograph carbon strip, the aims being a better wear problems anticipation and the creation of a preventive maintenance. For that, an electrical model is coupled to the thermal one to take into account all Joule effects. The ADI strategy enables a significant computation time reduction against most classical resolution methods. Besides, the model involves two mathematical processes: the first one is an appropriate variable transform which induces a fixed surface heat production, while the second is based on locally refined meshes. Various numerical tests are presented and discussed in order to show the accuracy of the scheme. From a physical point of view, the results are much interesting. Further investigations, depending on the different parameters, should lead us to predict the strip critical thermal phases.

Lactulose in the Management of Constipation: A Current Review

1992 ◽  
Vol 26 (10) ◽  
pp. 1277-1282 ◽  
Author(s):  
Theresa V. Kot ◽  
Ngaire A. Pettit-Young
Keyword(s):  
Clinical Trials ◽  
Adverse Effects ◽  
Clinical Studies ◽  
Data Extraction ◽  
Point Of View ◽  
Data Synthesis ◽  
Study Selection ◽  
Beneficial Response ◽  
A Current

OBJECTIVE: To review the current published clinical studies evaluating the clinical efficacy and safety of lactulose compared with other laxatives or placebo. Adverse effects associated with lactulose are also reported. DATA SOURCES: Information was retrieved by searching the MEDLINE and EMBASE databases for clinical trials, abstracts, conference proceedings, and review articles dealing with lactulose. STUDY SELECTION: Emphasis was placed on clinical trials where lactulose was compared with other laxatives or placebo in patient populations where the diagnosis of constipation was reasonably established. DATA EXTRACTION: The methodology and results from clinical studies were evaluated. Assessment of the studies was made based on diagnosis of constipation, prior management of patients, follow-up of patients, dosage, and adverse effects. DATA SYNTHESIS: Clinical trials in geriatric patients, terminally ill patients, children, and normal and constipated subjects were reviewed. In most instances, lactulose was compared with a placebo, without incorporating the current education on dietary techniques for improving defecation. CONCLUSIONS: Generally, clinical trials have demonstrated a beneficial response compared with placebo, although sometimes that response has been only marginally better, from a clinical point of view.

A Novel Combination of Adaptive Tools for Turbomachinery Airfoil Shape Optimization Using a Real-Coded Genetic Algorithm

2013 ◽  
Author(s):  
A. Safari ◽  
H. G. Lemu ◽  
M. Assadi
Keyword(s):  
Genetic Algorithm ◽  
Shape Optimization ◽  
Performance Enhancement ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Computation Time ◽  
Point Of View ◽  
Compressor Rotor ◽  
Real Coded Genetic Algorithm

An automated shape optimization methodology for a typical heavy-duty gas turbine (GT) compressor rotor blade section is presented in this paper. The approach combines a Non-Uniform Rational B-Spline (NURBS) driven parametric geometry description, a two-dimensional flow analysis, and a Genetic Algorithm (GA)-based optimization route. The objective is minimizing the total pressure losses for design condition as well as maximizing the airfoils operating range which is an assessment of the off-design behavior. To achieve the goal, design optimization process is carried out by coupling an established MATLAB code for the Differential Evolution (DE)-based optimum parameterized curve fitting of the measured point cloud of the airfoils’ shape, a blade-to-blade flow analysis in COMSOL Multiphysics, and a developed real-coded GA in MATLAB script. Using the combination of these adaptive tools and methods, the first results are considerably promising in terms of computation time, ability to extend the methodology for three-dimensional and multidisciplinary approach, and last but not least airfoil shape performance enhancement from efficiency and pressure rise point of view.

scholarly journals Mineral Trioxide Aggregate Applications in Endodontics: A Review

2020 ◽  
Vol 14 (04) ◽  
pp. 683-691
Author(s):  
Gabriele Cervino ◽  
Luigi Laino ◽  
Cesare D’Amico ◽  
Diana Russo ◽  
Ludovica Nucci ◽  
...  
Keyword(s):  
Root Resorption ◽  
Mineral Trioxide Aggregate ◽  
Point Of View ◽  
Dental Material ◽  
Clinical Aspects ◽  
Root Canal Therapy ◽  
Dental Tissues ◽  
Current Topic ◽  
Conservative Dentistry ◽  
A Current

AbstractA current topic in dentistry concerns the biocompatibility of the materials, and in particular, conservative dentistry and endodontics ones. The mineral trioxide aggregate (MTA) is a dental material with biocompatibility properties to oral and dental tissues. MTA was developed for dental root repair in endodontic treatment and it is formulated from commercial Portland cement, combined with bismuth oxide powder for radiopacity. MTA is used for creating apical plugs during apexification, repairing root perforations during root canal therapy, treating internal root resorption, and pulp capping. The objective of this article is to investigate MTA features from a clinical point of view, even compared with other biomaterials. All the clinical data regarding this dental material will be evaluated in this review article. Data obtained from the analysis of the past 10 years’ literature highlighted 19 articles in which the MTA clinical aspects could be recorded. The results obtained in this article are an important step to demonstrate the safety and predictability of oral rehabilitations with these biomaterials and to promote a line to improve their properties in the future.

Receivables Management

Upravlenie ◽  
2015 ◽  
Vol 3 (4) ◽  
pp. 41-48
Author(s):  
Тарасова ◽  
E. Tarasova
Keyword(s):  
Sharp Decrease ◽  
Point Of View ◽  
Real Economy ◽  
Its Analysis ◽  
Main Activity ◽  
A Current

The paper is devoted to problems of real economy organizations’ receivables management. The increasing of receivables management urgency owing to a sharp decrease of possibilities on external financial resources attracting for corporate purposes in recent years. In this paper different interpretations of the receivables concept and the author’s point of view have been considered, recommendations on the receivables management, arising from a current (main) activity, which associated with the sale of goods, works and services produced or provided by organization are given. Steps of the receivables management, approaches to its analysis for preceding report periods, the planning of receivables, standard and alternative methods of the receivables management are listed in this paper too.

Evolution of Pipe Properties During Reel-Lay Process: Experimental Characterisation and Finite Element Modelling

2005 ◽  
Author(s):  
Michae¨l Martinez ◽  
George Brown
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Computation Time ◽  
Material Model ◽  
Point Of View ◽  
Fatigue Properties ◽  
Geometrical Shape ◽  
Element Analysis ◽  
New Model ◽  
Tension And Compression

The development of finite element analysis, in terms of simulation power and theoretical model accuracy, enables one to understand and simulate industrial processes more precisely, especially those involving non linear behaviour and analysis. Reeled pipe technology is one of these, and has a lot to gain from this increasing efficiency. In the reel-lay process the pipe is first reeled onto a drum on a vessel for transportation. During offshore installation the pipe is unreeled, straightened and deployed into the sea. During the process, the pipe is fully and cyclically plastified. Plastification modifies the pipe properties, which is not by itself detrimental but should be understood by the designer. Pipe properties are affected in three ways: geometrical shape – reeling and straightening induce some residual ovalisation; mechanical properties – yield stress, hardening slope, isotropy are modified; and fatigue properties. Technip and IFP have studied these property evolutions for many years, both from an experimental and a numerical point of view. The present paper discusses the first two points. A wide experimental programme has been performed. Full scale pipes were reeled and straightened on a bending rig device especially built for that purpose. Pipe ovalisation was monitored through the whole process. Pipe mechanical properties were also fully characterised in the pipe axial, hoop and thickness directions, both in tension and compression, before and after reeling process. Extruded and UOE pipes were tested and characterised. Pipe initial properties are dependent on the manufacturing process but they are modified by the reeling process. Reeling induces some anisotropy that cannot be properly accounted for by usual plasticity models. Finite element simulations with Abaqus software, using the material behaviour of unreeled pipe, underestimate stiffness evolution in the hoop direction and overestimate ovalisation induced by the reeling process. Anisotropy has indeed a great effect on ovalisation that results from an interaction between axial and hoop loading. Hardening is also a key parameter. A new plasticity model has been written in an Abaqus User Material Model, known as UMAT. The new model is based on an anisotropic Hill criterion and special attention is paid to the hardening. This new model reduces by more than two the error on ovality estimation, and gives a realistic prediction of material anisotropy evolution through the process. Although, the tuning of the model coefficients is more complex than for usual models, its use is quite straightforward and does not increase computation time.

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