scholarly journals Hipparcos minor planets: Towards an improvement of the model analysis by detecting influence factors

1996 ◽  
Vol 172 ◽  
pp. 447-450 ◽  
Author(s):  
M. L. Bougeard ◽  
J.-F. Bange ◽  
M. Mahfouz ◽  
A. Bec-Borsenberger
Keyword(s):  
Variable Selection ◽  
Statistical Methods ◽  
Preliminary Data ◽  
Reference Frames ◽  
Model Building ◽  
Influence Factors ◽  
Model Analysis ◽  
Short Length ◽  
Minor Planets

In order to evaluate a possible rotation between the Hipparcos and the dynamical reference frames, Hipparcos minor planets preliminary data are analysed. The resolution of the problem is very sensitive to correlations induced by the short length of the interval of observation. Several statistical methods are performed to appreciate the factors of bad conditioning. A procedure for variable selection and model building is given.

Empirical Analysis of the Effects of Parasitic Magnetic Stray Field on Force Output of Electromagnetic Actuators

2016 ◽  
Vol 1140 ◽  
pp. 384-391 ◽  
Author(s):  
Andreas Heyder ◽  
Stefan Steinbeck ◽  
Matthaeus Brela ◽  
Alexander Meyer ◽  
Sandra Abersfelder ◽  
...  
Keyword(s):  
Statistical Methods ◽  
Model Building ◽  
Field Measurements ◽  
Relevant Information ◽  
Field Analysis ◽  
Stray Field ◽  
Force Output ◽  
Electromagnetic Actuators ◽  
Magnetic Actuators ◽  
Six Sigma Methodology

Electromagnetic actuators are used in a variety of technical applications especially in the automotive industry. In-line process control methods are an essential component of the Lean and Six Sigma methodology to ensure process quality. However, the current state of the art in process and quality control is largely limited to end-of-line measurements of the force output. Analysing the magnetic stray field is a promising method that can be used to draw conclusions on the properties and defects of the flux-conducting magnetic materials. This phenomenon can potentially be used to identify defects in magnetic actuators thus allowing inline quality-monitoring. In order to realize this feature, patterns in the magnetic stray field of an actuator have to be identified and linked to a specific defect. The resulting challenge is the analysis of large datasets in order to characterize the stray field anomalies. This paper summarizes the results of a study on linear magnetic actuators trying to prove a relationship between parasitic magnetic stray field and the overall force output of an actuator by analysing the data with statistical methods. The findings of this study suggest that certain statistical methods, like regression, are not well suited to build a prediction model for defects in actuators using a similar approach of measuring stray field outside the actuator. This is mainly due to the fact that prerequisites for model building are difficult to full fill within the context of stray field analysis. Nevertheless, the findings also suggest that methods of exploratory data analysis can be used to derive quality relevant information from data of stray field measurements. The paper elaborates on the problem of defining a population, choosing variables for model building, as well as model error.

scholarly journals Fundamental radio reference frame from VLA observations of minor planets

1988 ◽  
Vol 128 ◽  
pp. 97-97 ◽  
Author(s):  
G. H. Kaplan ◽  
K. J. Johnston ◽  
P. K. Seidelmann ◽  
C. M. Wade ◽  
T. S. Carroll
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Thermal Emission ◽  
Optical Observations ◽  
Minor Planets ◽  
Very Large Array ◽  
Test Particles ◽  
Optical Reference ◽  
Microwave Regime

The weak thermal emission from the largest minor planets can be detected in the microwave regime by the Very Large Array (VLA). Signal-to-noise ratios are sufficiently high to permit precise measurement of the positions of these objects at all points in their orbits with respect to background extragalactic sources. We are in the process of obtaining observations of astrometric accuracy for minor planets 1 Ceres, 2 Pallas, 4 Vesta, and 10 Hygeia.Minor planets have historically served as “test particles” in the solar system, and optical observations of these objects have been valuable in the determination of fundamental astronomical constants. In particular, optical observations of minor planets have played an important role in the establishment of the fundamental optical reference frame by permitting the determination of the orientation of the Earth's orbit relative to the stars defining the frame.Similarly, radio observations of these bodies can play a corresponding role in the establishment of a fundamental radio reference frame. Our observations will provide a direct link between the dynamical and radio reference frames, and provide important information on the relationship between the radio and optical reference frames.

Interplay of Gut Microbiota, Body Mass Index and Depression Scores in Anorexia Nervosa: Preliminary Data

2017 ◽  
Vol 41 (S1) ◽  
pp. S92-S92
Author(s):  
S. Mörkl ◽  
S. Lackner ◽  
G. Gorkiewicz ◽  
K. Kashofer ◽  
C. Blesl ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Gut Microbiota ◽  
Preliminary Data ◽  
Influence Factors ◽  
Alpha Diversity ◽  
Normal Weight ◽  
Psychiatric Disease ◽  
Significance Level ◽  
Study Results ◽  
Competing Interest

IntroductionAnorexia nervosa (AN) is a lethal psychiatric disease with only narrow treatment possibilities. Recent study results point out, that gut microbiota might be a contributing factor in the development and persistence of AN through effects on the gut-brain-axis.MethodsWe used 16SRNA sequencing to characterize the composition and diversity of the gut microbiota of 18 AN patients, 19 normal weight controls and 19 athletes matched by age using stool samples. The QIIME-pipeline was used to assess the sequencing result. All participants completed an activity-questionnaire (IPAQ) and inventories to measure depression (BDI, HAMD).ResultsKruskal-Wallis test identified significant differences in alpha-diversity (Chao-1-estimator [P = 0.013], number of observed species [P = 0.027]) between groups. Spearman-Correlation revealed a significant correlation of number of observed species (r = 0.366, P = 0.006) Chao-1-estimator (r = 0.352, P = 0.008) and BMI (Fig. 1). Furthermore, a higher BMI was related to lower depression scores (r = 0.351, P < 0.001). Although there was a tendency of a negative correlation of BDI-scores and alpha-diversity (r = –0.180, P = 0.059), correlations with depression scores and IPAQ-scores did not reach significance level (Fig. 1).ConclusionsOur preliminary data demonstrate correlations of alpha-diversity and BMI. Further studies are needed to provide further insights in AN gut microbiota and its influence factors.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Evaluation of alternative statistical methods for linear model analysis to compare two treatments for 24-hour blood pressure response

1992 ◽  
Vol 11 (14-15) ◽  
pp. 1843-1860 ◽  
Author(s):  
Elizabeth A. Turney ◽  
Ingrid A. Amara ◽  
Gary G. Koch ◽  
William H. Stewart
Keyword(s):  
Blood Pressure ◽  
Linear Model ◽  
Statistical Methods ◽  
Blood Pressure Response ◽  
Model Analysis ◽  
Pressure Response

Non-Standard Parametric Statistical Inference

2017 ◽  
Author(s):  
Russell Cheng
Keyword(s):  
Statistical Inference ◽  
Statistical Methods ◽  
Model Building ◽  
Parametric Bootstrap ◽  
Basic Knowledge ◽  
Standard Theory ◽  
Regularity Conditions ◽  
Parameter Estimates ◽  
Bootstrap Resampling ◽  
Distributional Properties

This book discusses the fitting of parametric statistical models to data samples. Emphasis is placed on (i) how to recognize situations where the problem is non-standard, when parameter estimates behave unusually, and (ii) the use of parametric bootstrap resampling methods in analysing such problems. Simple and practical model building is an underlying theme. A frequentist viewpoint based on likelihood is adopted, for which there is a well-established and very practical theory. The standard situation is where certain widely applicable regularity conditions hold. However, there are many apparently innocuous situations where standard theory breaks down, sometimes spectacularly. Most of the departures from regularity are described geometrically in the book, with mathematical detail only sufficient to clarify the non-standard nature of a problem and to allow formulation of practical solutions. The book is intended for anyone with a basic knowledge of statistical methods typically covered in a university statistical inference course who wishes to understand or study how standard methodology might fail. Simple, easy-to-understand statistical methods are presented which overcome these difficulties, and illustrated by detailed examples drawn from real applications. Parametric bootstrap resampling is used throughout for analysing the properties of fitted models, illustrating its ease of implementation even in non-standard situations. Distributional properties are obtained numerically for estimators or statistics not previously considered in the literature because their theoretical distributional properties are too hard to obtain theoretically. Bootstrap results are presented mainly graphically in the book, providing easy-to-understand demonstration of the sampling behaviour of estimators.

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