A priori experimental design for inverse identification of magnetic material properties of an electromagnetic device using uncertainty analysis

AbstractTargeted magnetic flux guidance in the rotor cross section of rotational electrical machines is crucial for the machine’s efficiency. Cutouts in the electrical steel sheets are integrated in the rotor sheets for magnetic flux guidance. These cutouts create thin structures in the rotor sheets which limit the maximum achievable rotational speed under centrifugal forces and the maximum energy density of the rotating electrical machine. In this paper, embossing-induced residual stress, employing the magneto-mechanical Villari effect, is studied as an innovative and alternative flux barrier design with negligible mechanical material deterioration. The overall objective is to replace cutouts by embossings, increasing the mechanical strength of the rotor. The identification of suitable embossing geometries, distributions and methodologies for the local introduction of residual stress is a major challenge. This paper examines finely distributed pyramidal embossings and their effect on the magnetic material behavior. The study is based on simulation and measurements of specimen with a single line of twenty embossing points performed with different punch forces. The magnetic material behavior is analyzed using neutron grating interferometry and a single sheet tester. Numerical examinations using finite element analysis and microhardness measurements provide a more detailed understanding of the interaction of residual stress distribution and magnetic material properties. The results reveal that residual stress induced by embossing affects magnetic material properties. Process parameters can be applied to adjust the magnetic material deterioration and the effect of magnetic flux guidance.

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On Adaptive Sampling for Single and Multi-Response Bayesian Surrogate Models

Volume 1: 32nd Design Automation Conference, Parts A and B ◽

10.1115/detc2006-99210 ◽

2006 ◽

Cited By ~ 9

Author(s):

David A. Romero ◽

Cristina H. Amon ◽

Susan Finger

Keyword(s):

Experimental Design ◽

Adaptive Sampling ◽

Design Space Exploration ◽

A Priori ◽

Computer Experiments ◽

Latin Hypercube Sampling ◽

Surrogate Models ◽

Sampling Techniques ◽

Design And Optimization ◽

Sampling Points

In order to reduce the time and resources devoted to design-space exploration during simulation-based design and optimization, the use of surrogate models, or metamodels, has been proposed in the literature. Key to the success of metamodeling efforts are the experimental design techniques used to generate the combinations of input variables at which the computer experiments are conducted. Several adaptive sampling techniques have been proposed to tailor the experimental designs to the specific application at hand, using the already-acquired data to guide further exploration of the input space, instead of using a fixed sampling scheme defined a priori. Though mixed results have been reported, it has been argued that adaptive sampling techniques can be more efficient, yielding better surrogate models with less sampling points. In this paper, we address the problem of adaptive sampling for single and multi-response metamodels, with a focus on Multi-stage Multi-response Bayesian Surrogate Models (MMBSM). We compare distance-optimal latin hypercube sampling, an entropy-based criterion and the maximum cross-validation variance criterion, originally proposed for one-dimensional output spaces and implemented in this paper for multi-dimensional output spaces. Our results indicate that, both for single and multi-response surrogate models, the entropy-based adaptive sampling approach leads to models that are more robust to the initial experimental design and at least as accurate (or better) when compared with other sampling techniques using the same number of sampling points.

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Topics of Controversy: An Empirical Analysis of Web Censorship Lists

Proceedings on Privacy Enhancing Technologies ◽

10.1515/popets-2017-0004 ◽

2017 ◽

Vol 2017 (1) ◽

pp. 42-61 ◽

Cited By ~ 4

Author(s):

Zachary Weinberg ◽

Mahmood Sharif ◽

Janos Szurdi ◽

Nicolas Christin

Keyword(s):

Experimental Design ◽

Empirical Analysis ◽

Experimental Technique ◽

A Priori ◽

Access Network ◽

Network Resources ◽

Internet Censorship

AbstractStudies of Internet censorship rely on an experimental technique called probing. From a client within each country under investigation, the experimenter attempts to access network resources that are suspected to be censored, and records what happens. The set of resources to be probed is a crucial, but often neglected, element of the experimental design.We analyze the content and longevity of 758,191 webpages drawn from 22 different probe lists, of which 15 are alleged to be actual blacklists of censored webpages in particular countries, three were compiled using a priori criteria for selecting pages with an elevated chance of being censored, and four are controls. We find that the lists have very little overlap in terms of specific pages. Mechanically assigning a topic to each page, however, reveals common themes, and suggests that handcurated probe lists may be neglecting certain frequently censored topics. We also find that pages on controversial topics tend to have much shorter lifetimes than pages on uncontroversial topics. Hence, probe lists need to be continuously updated to be useful.To carry out this analysis, we have developed automated infrastructure for collecting snapshots of webpages, weeding out irrelevant material (e.g. site “boilerplate” and parked domains), translating text, assigning topics, and detecting topic changes. The system scales to hundreds of thousands of pages collected.

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Effect of material properties on optimal radial strain gage locations in sharp V-notched configurations

MATEC Web of Conferences ◽

10.1051/matecconf/201817203002 ◽

2018 ◽

Vol 172 ◽

pp. 03002 ◽

Cited By ~ 1

Author(s):

Pranjol Paul ◽

K.S.R. Krishna Murthy ◽

Debabrata Chakraborty

Keyword(s):

Strain Gage ◽

Material Properties ◽

A Priori ◽

Radial Strain ◽

Numerical Approach ◽

Conference Paper ◽

Notch Angle ◽

Notch Stress ◽

Notch Length

A simple yet reliable and powerful methodology using only one strain gage has been recommended for appropriate determination of notch stress intensity factor (NSIF) for sharp V-notched configurations subjected to mode I condition. The methodology is supported by strong theoretical postulates, and it permits the gage to be pasted prominently apart from tip of the notch thus avoiding various problems associated with singularities. Unlike the conventional methodologies, the recommended strain gage methodology also proposes optimal radial strain gage locations which are beneficial in appropriate determination of NSIFs. A FEM based numerical approach is adopted for obtaining optimal radial gage locations a priori for the aforesaid configuration. The optimal radial gage locations are observed to be influenced by parameters viz. the notch angle, the ratio of notch length to width of the plate and also material properties. Results were already published by the authors to establish that the optimal radial gage locations are influenced by the notch angle and the ratio of notch length to width of the plate. In this conference paper, a case is studied with a completely different material to check whether material properties influence the graphical trends of results or not.

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Intuition and Inquiry

Essays in Philosophy ◽

10.5840/eip201213116 ◽

2012 ◽

Vol 13 (1) ◽

pp. 285-296

Author(s):

Anand Vaidya ◽

Keyword(s):

Experimental Design ◽

Recent Work ◽

A Priori ◽

Philosophical Methodology ◽

Philosophical Inquiry

Recent work in philosophical methodology by experimental philosophers has brought to light a certain kind of skepticism about the role of intuitions in a priori philosophical inquiry. In this paper I turn attention away from a priori philosophical inquiry and on to the role of intuition in experimental design. I argue that even if we have reason to be skeptical about the role of intuition in a priori philosophical inquiry, we cannot remove intuition from inquiry altogether, because appeals to intuition are essential for experimental design.

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Analytical approximation of the dependence of magnetic material properties on temperature

COMPEL The International Journal for Computation and Mathematics in Electrical and Electronic Engineering ◽

10.1108/03321649810203350 ◽

1998 ◽

Vol 17 (3) ◽

pp. 402-406 ◽

Cited By ~ 1

Author(s):

Z. Wl§odarski ◽

J. Wl§odarska

Keyword(s):

Magnetic Material ◽

Material Properties ◽

Analytical Approximation

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A Comparative Study of the Probabilistic-Collocation and Experimental-Design Methods for Petroleum-Reservoir Uncertainty Quantification

SPE Journal ◽

10.2118/140738-pa ◽

2011 ◽

Vol 16 (02) ◽

pp. 429-439 ◽

Cited By ~ 29

Author(s):

Heng Li ◽

Pallav Sarma ◽

Dongxiao Zhang

Keyword(s):

Experimental Design ◽

Uncertainty Analysis ◽

Uncertainty Quantification ◽

Large Scale ◽

Convergence Rates ◽

Discrete Distributions ◽

Data Uncertainty ◽

Reservoir Modeling ◽

Petroleum Reservoir ◽

Probabilistic Collocation

Summary Reservoir modeling and simulation are subject to significant uncertainty, which usually arises from heterogeneity of the geological formation and deficiency of measured data. Uncertainty quantification, thus, plays an important role in reservoir simulation. In order to perform accurate uncertainty analysis, a large number of simulations are often required. However, it is usually prohibitive to do so because even a single simulation of practical large-scale simulation models may be quite time consuming. Therefore, efficient approaches for uncertainty quantification are a necessity. The experimental-design (ED) method is applied widely in the petroleum industry for assessing uncertainties in reservoir production and economic appraisal. However, a key disadvantage of this approach is that it does not take into account the full probability-density functions (PDFs) of the input random parameters consistently—that is, the full PDFs are not used for sampling and design but used only during post-processing, and there is an inherent assumption that the distributions of these parameters are uniform (during sampling), which is rarely the case in reality. In this paper, we propose an approach to deal with arbitrary input probability distributions using the probabilistic-collocation method (PCM). Orthogonal polynomials for arbitrary distributions are first constructed numerically, and then PCM is used for uncertainty propagation. As a result, PCM can be applied efficiently for any arbitrary numerical or analytical distribution of the input parameters. It can be shown that PCM provides optimal convergence rates for linear models, whereas no such guarantees are provided by ED. The approach is also applicable to discrete distributions. PCM and ED are compared on a few synthetic and realistic reservoir models. Different types of PDFs are considered for a number of reservoir parameters. Results indicate that, while the computational efforts are greatly reduced compared to Monte Carlo (MC) simulation, PCM is able to accurately quantify uncertainty of various reservoir performance parameters. Results also reveal that PCM is more robust, more accurate, and more efficient than ED for uncertainty analysis.

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Numerical modelling of a flux-barrier SynchRel motor including punching effect

COMPEL The International Journal for Computation and Mathematics in Electrical and Electronic Engineering ◽

10.1108/compel-03-2016-0090 ◽

2016 ◽

Vol 35 (6) ◽

pp. 2022-2034 ◽

Cited By ~ 1

Author(s):

Marcin Lefik ◽

Zbigniew Gmyrek

Keyword(s):

Magnetic Material ◽

Numerical Modelling ◽

Low Power ◽

Material Properties ◽

Fractional Power ◽

Operating Parameters ◽

Content Type ◽

Damaged Zone ◽

Analytical Algorithm ◽

The Impact

Purpose Estimating the punching process’s impact on the operating parameters of an electrical motor is a special problem especially in the case of fractional power motors. The purpose of this paper is to discuss a method of numerical modelling that is useful for this case. Design/methodology/approach The proposed multi-physical FEM approach is based on using professional software in the process of modelling and determining the operating parameters of a low power motor. The basic elements of the approach are built FEM models for which the parameters characterising the damaged portions of the magnetic material were determined. The material properties of this zone were determined both by measurement and by a new analytical approach described in this paper. Findings The paper formulates the impact of punching on the operating parameters of a low power motor. Moreover, it formulates the analytical algorithm for the estimation of properties of material in damaged zones. Research limitations/implications Experimental verification will still be needed to check the model’s accuracy and applicability to various magnetic materials. Practical implications The paper provides an easy approach enabling the calculation of motor operating parameters and a simple and useful algorithm to estimate magnetic material properties in the damaged zone. Originality/value The analytical algorithm, as presented here, in conjunction with the measurement results is useful and applicable to estimating the magnetic material properties, which form the basis for accurate FEM calculation.

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