scholarly journals Methodology of non-linear robust estimation for the solutions synthesis of inverse and direct multidisciplinary problems in engineering dimensional chains calculation based on discrete analog data

2020 ◽  
pp. 70-88
Author(s):  
Iryna Trofymova ◽  
Ievgen Meniailov ◽  
Serhii Chernysh ◽  
Sergiy Yepifanov ◽  
Olexandr Khustochka ◽  
...  
Keyword(s):  
Robust Estimation ◽  
A Priori ◽  
Discrete Analog ◽  
Discrete Analogue ◽  
Estimation Methods ◽  
Regression Equations ◽  
Parametric Data ◽  
Non Linear ◽  
Definition Of ◽  
Direct Problems

This paper analyses the definition of inverse and direct problems in engineering dimensional chains calculation based on discrete analogue data and the methodologies for solving these problems. It is shown that the direct dimensional chains calculation, which belongs to the class of inverse boundary value problems in a stochastic formulation, can be transformed into multi-criteria problems of stochastic optimization with mixed conditions. The new multi-step solutions search methodology for these problems is based on non-linear robust estimation methods. It can be achieved through hierarchical two-level decisions synthesis scheme development. At the first step, this scheme includes identification of surrogate models (in the form of regression equations). At the second step, the effective robust estimates are computed to determine unknown values; estimations of unknown quantities are carried out under a priori and parametric data uncertainties. Results of calculations of inverse and direct problems in engineering dimensional chains for two-stage axial compressors are presented. They were obtained using interactive computer systems for decision-making support “ROD&IDS”.

Web-based Tools for Drug Repurposing: Successful Examples of Collaborative Research

2020 ◽  
Vol 28 (1) ◽  
pp. 181-195
Author(s):  
Quentin Vanhaelen
Keyword(s):  
User Interfaces ◽  
Collaborative Research ◽  
Meta Analysis ◽  
A Priori ◽  
Drug Repurposing ◽  
Data Access ◽  
Estimation Methods ◽  
Large Set ◽  
Computational Tools ◽  
Web Based

: Computational approaches have been proven to be complementary tools of interest in identifying potential candidates for drug repurposing. However, although the methods developed so far offer interesting opportunities and could contribute to solving issues faced by the pharmaceutical sector, they also come with their constraints. Indeed, specific challenges ranging from data access, standardization and integration to the implementation of reliable and coherent validation methods must be addressed to allow systematic use at a larger scale. In this mini-review, we cover computational tools recently developed for addressing some of these challenges. This includes specific databases providing accessibility to a large set of curated data with standardized annotations, web-based tools integrating flexible user interfaces to perform fast computational repurposing experiments and standardized datasets specifically annotated and balanced for validating new computational drug repurposing methods. Interestingly, these new databases combined with the increasing number of information about the outcomes of drug repurposing studies can be used to perform a meta-analysis to identify key properties associated with successful drug repurposing cases. This information could further be used to design estimation methods to compute a priori assessment of the repurposing possibilities.

scholarly journals Aerosol-based antimicrobial photoinactivation in the lungs: an action spectrum study

2021 ◽  
Author(s):  
Chiara Treghini ◽  
Alfonso Dell’Accio ◽  
Franco Fusi ◽  
Giovanni Romano
Keyword(s):  
Light Source ◽  
A Priori ◽  
Action Spectrum ◽  
Multidrug Resistant ◽  
Theoretical Modelling ◽  
Resistant Bacteria ◽  
Lung Infections ◽  
Killing Action ◽  
Definition Of

AbstractChronic lung infections are among the most diffused human infections, being often associated with multidrug-resistant bacteria. In this framework, the European project “Light4Lungs” aims at synthesizing and testing an inhalable light source to control lung infections by antimicrobial photoinactivation (aPDI), addressing endogenous photosensitizers only (porphyrins) in the representative case of S. aureus and P. aeruginosa. In the search for the best emission characteristics for the aerosolized light source, this work defines and calculates the photo-killing action spectrum for lung aPDI in the exemplary case of cystic fibrosis. This was obtained by applying a semi-theoretical modelling with Monte Carlo simulations, according to previously published methodology related to stomach infections and applied to the infected trachea, bronchi, bronchioles and alveoli. In each of these regions, the two low and high oxygen concentration cases were considered to account for the variability of in vivo conditions, together with the presence of endogenous porphyrins and other relevant absorbers/diffusers inside the illuminated biofilm/mucous layer. Furthermore, an a priori method to obtain the “best illumination wavelengths” was defined, starting from maximizing porphyrin and light absorption at any depth. The obtained action spectrum is peaked at 394 nm and mostly follows porphyrin extinction coefficient behavior. This is confirmed by the results from the best illumination wavelengths, which reinforces the robustness of our approach. These results can offer important indications for the synthesis of the aerosolized light source and definition of its most effective emission spectrum, suggesting a flexible platform to be considered in further applications.

Toward a Functional Definition of the A Priori

1944 ◽  
Vol 41 (6) ◽  
pp. 155
Author(s):  
Arthur Child
Keyword(s):  
A Priori ◽  
Definition Of

Subject of Economic Science

2015 ◽  
pp. 115-120
Author(s):  
D. Egorov
Keyword(s):  
Human Behavior ◽  
Classical Theory ◽  
Adam Smith ◽  
A Priori ◽  
Economic Science ◽  
The Public ◽  
Public Consciousness ◽  
Wealth Of Nations ◽  
Definition Of ◽  
The Relationship

Adam Smith defined economics as “the science of the nature and causes of the wealth of nations” (implicitly appealing – in reference to the “wealth” – to the “value”). Neo-classical theory views it as a science “which studies human behavior in terms of the relationship between the objectives and the limited funds that may have a different use of”. The main reason that turns the neo-classical theory (that serves as the now prevailing economic mainstream) into a tool for manipulation of the public consciousness is the lack of measure (elimination of the “value”). Even though the neo-classical definition of the subject of economics does not contain an explicit rejection of objective measures the reference to “human behavior” inevitably implies methodological subjectivism. This makes it necessary to adopt a principle of equilibrium: if you can not objectively (using a solid measurement) compare different states of the system, we can only postulate the existence of an equilibrium point to which the system tends. Neo-classical postulate of equilibrium can not explain the situation non-equilibrium. As a result, the neo-classical theory fails in matching microeconomics to macroeconomics. Moreover, a denial of the category “value” serves as a theoretical basis and an ideological prerequisite of now flourishing manipulative financial technologies. The author believes in the following two principal definitions: (1) economics is a science that studies the economic system, i.e. a system that creates and recombines value; (2) value is a measure of cost of the object. In our opinion, the value is the information cost measure. It should be added that a disclosure of the nature of this category is not an obligatory prerequisite of its introduction: methodologically, it is quite correct to postulate it a priori. The author concludes that the proposed definitions open the way not only to solve the problem of the measurement in economics, but also to address the issue of harmonizing macro- and microeconomics.

scholarly journals Machine Learning for Turbulence Model Development Using a High-Fidelity HPT Cascade Simulation

2017 ◽  
Author(s):  
Jack Weatheritt ◽  
Richard Pichler ◽  
Richard D. Sandberg ◽  
Gregory Laskowski ◽  
Vittorio Michelassi
Keyword(s):  
High Pressure ◽  
Evolutionary Algorithm ◽  
Turbine Blade ◽  
A Priori ◽  
Model Development ◽  
Boussinesq Approximation ◽  
High Pressure Turbine ◽  
Stress Strain ◽  
Non Linear ◽  
Anisotropy Tensor

The validity of the Boussinesq approximation in the wake behind a high-pressure turbine blade is explored. We probe the mathematical assumptions of such a relationship by employing a least-squares technique. Next, we use an evolutionary algorithm to modify the anisotropy tensor a priori using highly resolved LES data. In the latter case we build a non-linear stress-strain relationship. Results show that the standard eddy-viscosity assumption underpredicts turbulent diffusion and is theoretically invalid. By increasing the coefficient of the linear term, the farwake prediction shows minor improvement. By using additional non-linear terms in the stress-strain coupling relationship, created by the evolutionary algorithm, the near-wake can also be improved upon. Terms created by the algorithm are scrutinized and the discussion is closed by suggesting a tentative non-linear expression for the Reynolds stress, suitable for the wake behind a high-pressure turbine blade.

scholarly journals Extracting real-crack properties from non-linear elastic behaviour of rocks: abundance of cracks with dominating normal compliance and rocks with negative Poisson ratios

2017 ◽  
Vol 24 (3) ◽  
pp. 543-551 ◽  
Author(s):  
Vladimir Y. Zaitsev ◽  
Andrey V. Radostin ◽  
Elena Pasternak ◽  
Arcady Dyskin
Keyword(s):  
Experimental Data ◽  
Poisson Ratio ◽  
A Priori ◽  
Elastic Behaviour ◽  
Crack Model ◽  
Normal Compliance ◽  
S Wave ◽  
Linear Elastic ◽  
Non Linear ◽  
Linear Elastic Behaviour

Abstract. Results of examination of experimental data on non-linear elasticity of rocks using experimentally determined pressure dependences of P- and S-wave velocities from various literature sources are presented. Overall, over 90 rock samples are considered. Interpretation of the data is performed using an effective-medium description in which cracks are considered as compliant defects with explicitly introduced shear and normal compliances without specifying a particular crack model with an a priori given ratio of the compliances. Comparison with the experimental data indicated abundance (∼ 80 %) of cracks with the normal-to-shear compliance ratios that significantly exceed the values typical of conventionally used crack models (such as penny-shaped cuts or thin ellipsoidal cracks). Correspondingly, rocks with such cracks demonstrate a strongly decreased Poisson ratio including a significant (∼ 45 %) portion of rocks exhibiting negative Poisson ratios at lower pressures, for which the concentration of not yet closed cracks is maximal. The obtained results indicate the necessity for further development of crack models to account for the revealed numerous examples of cracks with strong domination of normal compliance. Discovering such a significant number of naturally auxetic rocks is in contrast to the conventional viewpoint that occurrence of a negative Poisson ratio is an exotic fact that is mostly discussed for artificial structures.

scholarly journals THE WAYS OF TECHNICAL REALIZATION OF ADAPTIVE ALGORITHM OF COMPENSATION OF NON-LINEAR DISTORTIONS OF RADIO DEVICES

2018 ◽  
Vol 6 (52) ◽  
pp. 140-143
Author(s):  
О. Shefer ◽  
N. Ichanska ◽  
B. Topikha ◽  
V. Shefer
Keyword(s):  
Adaptive Systems ◽  
Adaptive Filters ◽  
A Priori ◽  
Weather Conditions ◽  
Adaptive Method ◽  
Theory And Practice ◽  
Modern Theory ◽  
Additional Advantage ◽  
Local Systems ◽  
Non Linear

The practical realization of potential opportunities of onboard radio local systems of radio local systems (OBRLS) that are currently considerably higher than their real approachable technical characteristics is one of the main tasks of modern theory and practice of electronic and telecommunication. The authors of the article proposed some specific technical offers and ways of physical realization of scientifically grounded algorithm of adaptive compensation of non linear distortions (ACNLD). The insertion of artificial main and supportive entrances into the scheme of non-linear adaptive compensators allowed using the general theory of adaptive systems for their synthesis. The practical usage of synthesized following such a principle ACNLD according to the created recommendations allows to significantly increase the indices of quality of OBRLS in the real conditions of their functioning, comparing with the already known ones. An additional advantage of proposed adaptive method of expansion of linear dynamic diapason (LDD) is an improvement of all-weather of OBRLS and increasing of probability of identification of radio local maps of locality captured in different weather conditions without any additional changeovers. Except for this, a flexible reserve for the noise immunity of OBRLS is being fulfilled that allows taking into consideration the possible improvements of means of radio electronic struggle. Synthesized ACNLD are considerably free from many drawbacks of linear determined means of expansion of dynamic diapason of radio receiving devices (RRD) and also they have simpler apparatus realization. Except, in a process of projection of ACNLD a considerably less volume of a priori information about the parameters of LDD is needed for the calculation of already known schemes of depression of non-linear distortions. The transferring functions of adaptive filters of ACNLD are quite quickly gather at the non-linear transferring function of radio device (RD) provided that an effective convergence can be seen only with the presence of the inner noises at least unless they exceed the non-linear distortions by the level.

scholarly journals Autoregressive Models of the Random fields—A Survey

2020 ◽  
pp. 1-9
Keyword(s):  
Random Fields ◽  
Linear Models ◽  
Estimation Methods ◽  
Suitable Model ◽  
Main Mode ◽  
One Dimensional ◽  
Non Linear ◽  
The Status ◽  
Ar Models ◽  
Shed Light

Autoregressive (AR) random fields are widely use to describe changes in the status of real-physical objects and implemented for analyzing linear & non-linear models. AR models are Markov processes with a higher order dependence for one-dimensional time series. Actually, various estimation methods were used in order to evaluate the autoregression parameters. Although in many applications background knowledge can often shed light on the search for a suitable model, but other applications lack this knowledge and often require the type of trial errors to choose a model. This article presents a brief survey of the literatures related to the linear and non-linear autoregression models, including several extensions of the main mode models and the models developed. The use of autoregression to describe such system requires that they be of sufficiently high orders which leads to increase the computational costs.

scholarly journals A Discrete Analog of the Lyapunov Function for Hyperbolic Systems

2018 ◽  
Vol 64 (4) ◽  
pp. 591-602
Author(s):  
R D Aloev ◽  
M U Khudayberganov
Keyword(s):  
Lyapunov Function ◽  
Hyperbolic Systems ◽  
A Priori ◽  
A Priori Estimate ◽  
Discrete Analog ◽  
Priori Estimate ◽  
Constant Coefficients ◽  
The Difference ◽  
Dissipative Boundary ◽  
Linear Hyperbolic System

We study the difference splitting scheme for the numerical calculation of stable solutions of a two-dimensional linear hyperbolic system with dissipative boundary conditions in the case of constant coefficients with lower terms. A discrete analog of the Lyapunov function is constructed and an a priori estimate is obtained for it. The obtained a priori estimate allows us to assert the exponential stability of the numerical solution.

The Static Aeroelasticity of Slender Configurations

1963 ◽  
Vol 14 (1) ◽  
pp. 75-104 ◽  
Author(s):  
G. J. Hancock
Keyword(s):  
Static Stability ◽  
Aerodynamic Forces ◽  
Flexible Aircraft ◽  
The Past ◽  
Plate Models ◽  
Non Linear ◽  
The Future ◽  
Static Aeroelasticity ◽  
Definition Of ◽  
Image Position

SummaryThe validity and applicability of the static margin (stick fixed) Kn,where as defined by Gates and Lyon is shown to be restricted to the conventional flexible aircraft. Alternative suggestions for the definition of static margin are put forward which can be equally applied to the conventional flexible aircraft of the past and the integrated flexible aircraft of the future. Calculations have been carried out on simple slender plate models with both linear and non-linear aerodynamic forces to assess their static stability characteristics.

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