828 research outputs found
A new behavioural model for performance evaluation of common mode chokes
A galvanically isolated three-phase AC/AC converter with a high-frequency AC-link has been analyzed from an EMC point of view. This is a special configuration because of a large number of switches, a high frequency transformer, and a fourwire output. The essential coupling paths are identified.
Corresponding suppression remedies are given. The results, before and after measures, have been presented to demonstrate the improvement in EMC.
Keywords: AC/AC converter; electromagnetic interference; galvanically isolate
Performance optimization aspects of common mode chokes
Optimization aspects of common mode chokes are presented. These are based on a behavioral model for common mode chokes and its sensitivity study. Results are used to show the influence of the designable parameters on the final performance of the choke placed in a circuit
Linear Categorical Marginal Modeling of solicited symptoms in vaccine clinical trials
Analysis of the occurrence of adverse events, and in particular of solicited symptoms, following vaccination is often needed for the safety and benefit-risk evaluation of any candidate vaccine, and typically involves taking repeated measurements. In this article, it is shown that Linear Categorical Marginal Models (LCMMs) are well suited to take into account the dependencies in the data arising from the repeated measurements and provide detailed and useful information for comparing safety profiles of different products while remaining relatively easy to interpret. LCMMs are presented and applied to a Phase III clinical trial of a candidate meningococcal pediatric vaccine
Foot placement variables of pedestrians in community setting during curve walking
Background: There is no precise description of changes of gait during curve walking. Research in curve walking is exclusively performed in clinical settings. Research question: Is there a difference in foot placement variables between the inner- and the outer leg during curve walking in a natural environment? And are these differences correlated with time or the curvature of the path? Method: During this observational study, camera footage was shot on a crossing where pedestrians were not aware of being filmed. Participants (n = 21, male, 18?40 yrs) were selected from this video footage. Using the software package ?Movieprocessing?, the kinematic variables (time, curvature, stride length, step length, step width and relative foot angle (RFA)) were extracted from the collected data. A MANOVA and Pearson correlation test were performed to explore the data. Results: MANOVA showed no significant differences in stride length and step length between inner- and outer leg. In contrast, a significant difference between the inner (M = 0.06, SD = 0.05) and outer leg (M = 0.10, SD = 0.06, F(20,256) = 3.577, p < .001) for the step width, and the inner (M = 11.72, SD = 7.99) and outer leg (M = 11.30, SD = 8.07, F(20,256) = 4.542, p < .001) for RFA was found. Pearson correlation was significant for curvature and step width for both legs pooled (r = .28, p < .01) and the outer leg (r = .64, p < .01), as well for time and RFA in the inner (r= -.25, p < .01) and outer leg (r = .213, p < .01). Significance: This research funds further research in curve walking in natural conditions, since curve walking is found to be performed non-symmetrically and not determined by geometrics but by choice. Foot placement variables change gradually and differently for both legs during walking a curve
Model comportemental pour l`evaluation des performances de chokes de mode commun
Un model comportemental pour lâĂ©valuation des performances de choke de mode commun (CMC) est proposĂ© : la topologie et les mĂ©thodes utilisĂ©s pour modĂ©liser les diffĂ©rentes propriĂ©tĂ©s de la CMC sont dĂ©crites. Il sâagit de la combinaison dâune modĂ©lisation prĂ©cise de la permĂ©abilitĂ© complexe du matĂ©riau, de la saturation, des inductances de fuite et des capacitĂ©s parasites. Les donnĂ©es necessaries fournies par le designer sont les valeurs de courants, tensions et impĂ©dances du systĂšme actuel sans CMC et des paramĂštres disponibles dans la littĂ©rature et /ou des manufacturiers en ce qui concerne la CMC modĂ©lisĂ©e. Ce model comportemental sâavĂšre essentiel dans la simulation des effets des interfĂ©rences Ă©lectromagnĂ©tiques (EMI)
Binary Models for Marginal Independence
Log-linear models are a classical tool for the analysis of contingency
tables. In particular, the subclass of graphical log-linear models provides a
general framework for modelling conditional independences. However, with the
exception of special structures, marginal independence hypotheses cannot be
accommodated by these traditional models. Focusing on binary variables, we
present a model class that provides a framework for modelling marginal
independences in contingency tables. The approach taken is graphical and draws
on analogies to multivariate Gaussian models for marginal independence. For the
graphical model representation we use bi-directed graphs, which are in the
tradition of path diagrams. We show how the models can be parameterized in a
simple fashion, and how maximum likelihood estimation can be performed using a
version of the Iterated Conditional Fitting algorithm. Finally we consider
combining these models with symmetry restrictions
Measurement of the CMS Magnetic Field
The measurement of the magnetic field in the tracking volume inside the
superconducting coil of the Compact Muon Solenoid (CMS) detector under
construction at CERN is done with a fieldmapper designed and produced at
Fermilab. The fieldmapper uses 10 3-D B-sensors (Hall probes) developed at
NIKHEF and calibrated at CERN to precision 0.05% for a nominal 4 T field. The
precise fieldmapper measurements are done in 33840 points inside a cylinder of
1.724 m radius and 7 m long at central fields of 2, 3, 3.5, 3.8, and 4 T. Three
components of the magnetic flux density at the CMS coil maximum excitation and
the remanent fields on the steel-air interface after discharge of the coil are
measured in check-points with 95 3-D B-sensors located near the magnetic flux
return yoke elements. Voltages induced in 22 flux-loops made of 405-turn
installed on selected segments of the yoke are sampled online during the entire
fast discharge (190 s time-constant) of the CMS coil and integrated offline to
provide a measurement of the initial magnetic flux density in steel at the
maximum field to an accuracy of a few percent. The results of the measurements
made at 4 T are reported and compared with a three-dimensional model of the CMS
magnet system calculated with TOSCA.Comment: 4 pages, 5 figures, 15 reference
Constraints on a Massive Dirac Neutrino Model
We examine constraints on a simple neutrino model in which there are three
massless and three massive Dirac neutrinos and in which the left handed
neutrinos are linear combinations of doublet and singlet neutrinos. We examine
constraints from direct decays into heavy neutrinos, indirect effects on
electroweak parameters, and flavor changing processes. We combine these
constraints to examine the allowed mass range for the heavy neutrinos of each
of the three generations.Comment: latex, 29 pages, 7 figures (not included), MIT-CTP-221
The Gross--Llewellyn Smith Sum Rule in the Analytic Approach to Perturbative QCD
We apply analytic perturbation theory to the Gross--Llewellyn Smith sum rule.
We study the evolution and the renormalization scheme dependence of the
analytic three-loop QCD correction to this sum rule, and demonstrate that the
results are practically renormalization scheme independent and lead to rather
different evolution than the standard perturbative correction possesses.Comment: 17 pages, 9 eps figures, REVTe
Revising Neutrino Oscillation Parameter Space With Direct Flavor-Changing Interactions
We formulate direct, neutrino flavor-changing interactions in a framework
that fits smoothly with the parameterization of two-and three-state mixing of
massive neutrino states. We show that even small direct interaction strengths
could have important consequences for the interpretation of currently running
and proposed oscillation experiments. The oscillation amplitude and the borders
of the allowed regions in two-and three-flavor mixing parameter space can be
sensitieve to the presence of direct interactions when the transition
probability is small. We use extensively the high sensitivity of the NOMAD
experiment to illustrate potentially large effects from small, direct flavor
violation. In the purely leptonic sector, we find that the clean muon neutrino
and electron neutrino beams from a muon collider could provide the sharpest
tests of direct flavor violation.Comment: 16 pages, 10 figure
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