scholarly journals Semantic Mediation for A Posteriori Log Analysis

Author(s):  
Farah Dernaika ◽  
Nora Cuppens-Boulahia ◽  
Frédéric Cuppens ◽  
Olivier Raynaud
Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1356
Author(s):  
Kyungbok Sung ◽  
Kyoung-Wook Min ◽  
Jeongdan Choi ◽  
Byung-Cheol Kim

We propose a log analysis framework for test driving of autonomous vehicles. The log of a vehicle is a fundamental source to detect and analyze events during driving. A set of dumped logs are, however, usually mixed and fragmented since they are generated concurrently by a number of modules such as sensors, actuators and programs. This makes it hard to analyze them to discover latent errors that could occur due to complex chain reactions among those modules. Our framework provides a logging architecture based on formal specifications, which hierarchically organizes them to find out a priori relationships between them. Then, algorithmic or implementation errors can be detected by examining a posteriori relationships. However, a test in a situation of certain parameters, so called an oracle test, does not necessarily trigger latent violations of the relationships. In our framework, this is remedied by adopting metamorphic testing to quantitatively verify the formal specification. As a working proof, we define three metamorphic relations critical for testing autonomous vehicles and verify them in a quantitative manner based on our logging system.


Author(s):  
Arno J. Bleeker ◽  
Mark H.F. Overwijk ◽  
Max T. Otten

With the improvement of the optical properties of the modern TEM objective lenses the point resolution is pushed beyond 0.2 nm. The objective lens of the CM300 UltraTwin combines a Cs of 0. 65 mm with a Cc of 1.4 mm. At 300 kV this results in a point resolution of 0.17 nm. Together with a high-brightness field-emission gun with an energy spread of 0.8 eV the information limit is pushed down to 0.1 nm. The rotationally symmetric part of the phase contrast transfer function (pctf), whose first zero at Scherzer focus determines the point resolution, is mainly determined by the Cs and defocus. Apart from the rotationally symmetric part there is also the non-rotationally symmetric part of the pctf. Here the main contributors are not only two-fold astigmatism and beam tilt but also three-fold astigmatism. The two-fold astigmatism together with the beam tilt can be corrected in a straight-forward way using the coma-free alignment and the objective stigmator. However, this only works well when the coefficient of three-fold astigmatism is negligible compared to the other aberration coefficients. Unfortunately this is not generally the case with the modern high-resolution objective lenses. Measurements done at a CM300 SuperTwin FEG showed a three fold-astigmatism of 1100 nm which is consistent with measurements done by others. A three-fold astigmatism of 1000 nm already sinificantly influences the image at a spatial frequency corresponding to 0.2 nm which is even above the point resolution of the objective lens. In principle it is possible to correct for the three-fold astigmatism a posteriori when through-focus series are taken or when off-axis holography is employed. This is, however not possible for single images. The only possibility is then to correct for the three-fold astigmatism in the microscope by the addition of a hexapole corrector near the objective lens.


2005 ◽  
Author(s):  
Damon U. Bryant ◽  
Ashley K. Smith ◽  
Sandra G. Alexander ◽  
Kathlea Vaughn ◽  
Kristophor G. Canali

2020 ◽  
Vol 7 (3) ◽  
pp. 1-27
Author(s):  
Denilson Junio Marques Soares ◽  
Paulo César Emiliano ◽  
Talita Emidio Andrade Soares
Keyword(s):  

O Departamento de Matemática da Universidade Federal de Viçosa tem realizado algumas medidas de prevenção à reprovação dos estudantes na disciplina de Cálculo, cujos índices têm assustado os professores. Uma dessas medidas está na elaboração de avaliações de matemática básica que objetivam identificar estudantes propensos à reprovação, a fim de proporcionar uma intervenção pedagógica capaz de reverter esta situação. Tendo em vista a importância desta avaliação como parte integrante dos processos de ensino e aprendizagem da disciplina, o presente artigo tem como objetivo oferecer uma análise estatística, pautada nas duas vertentes da Psicometria moderna: a Teoria Clássica dos Testes (TCT) e a Teoria de Resposta ao Item (TRI), e uma análise pedagógica dos descritores e distratores de alguns itens-chave que compõem uma dessas avaliações, escolhida para um estudo de caso. Os resultados apontaram para uma avaliação composta por itens com variados índices de dificuldade e, no geral, com bom poder discriminativo tanto pela análise via TCT, quanto pela TRI, cujos resultados foram obtidos através da estimação, pelo método da média a posteriori, de um modelo logístico de dois parâmetros. A consistência interna da avaliação como instrumento de mensuração de habilidades foi verificada pelo coeficiente alpha de Cronbach, assegurando a qualidade e confiabilidade dos resultados deste estudo. Espera-se que este trabalho sirva como um instrumento de difusão das teorias psicométricas na análise da estrutura de avaliações e aponte para a necessidade de uma maior discussão pedagógica acerca das possíveis lacunas existentes na aprendizagem de matemática básica dos estudantes do ensino superior.


Author(s):  
Heinrich Schepers ◽  
Giorgio Tonelli ◽  
Rudolf Eisler
Keyword(s):  
A Priori ◽  

1982 ◽  
Vol 21 (1) ◽  
pp. 83-84
Author(s):  
Karol J. Krotki

The publication reviewed is number 9 in the series" Applied Statistics and Econometrics" edited by Gerhard Tintner, Pierre Desire Truonet, and Heinrich Strecker. The purpose of the series is to publish papers " too long for ordinary journal articles, but not long enough for books . ... . . Upon acceptance, speedy publication can be promised". The abstracts in English, French, and German, usual in this series, are missing from the copy reviewed. The book consists of ten chapters: sampling theory; multi -stage sampling and other fundamental problems; optimum stratification; variances; sampling with replacement and other theoretical issues; experimental design; information theory; a posteriori raising factors ; order statistics; Bayesian methods. Such an ambitious content within 130 pages requires parsimonious presentation. One chapter has been squeezed into hardly more than four pages. The chapter on a posteriori raising factors will be useful in developing countries and particularly when samples do not work out as designed. It will also be refreshing to those limited to the literature in the English language.


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