822 research outputs found
Lifetime impact identification for continuous improvement of wind farm performance
To become profitable, the cost of offshore windfarms must be reduced. Optimization of the Operations & Maintenance process offers a great potential for cost reductions, especially for existing windfarm. As Continuous Improvement may deliver these cost reductions, this paper aims at fostering CI in the offshore wind industry. In order to identify where to focus CI efforts, we turn to the theory of Asset Life Cycle Management which shows that a shared multidisciplinary understanding of the complete lifetime of a windfarm is critical. Based on a case study at a leading offshore wind farm company, it is concluded that the Lifetime Impact Identification Analysis delivers such a shared understanding by bringing employees from different backgrounds together. Based on this understanding, CI priorities can be set and management may become proactive instead of having to do âfire-fightingâ
Scale-invariant segmentation of dynamic contrast-enhanced perfusion MR-images with inherent scale selection
Selection of the best set of scales is problematic when developing signaldriven
approaches for pixel-based image segmentation. Often, different
possibly conflicting criteria need to be fulfilled in order to obtain the best tradeoff
between uncertainty (variance) and location accuracy. The optimal set of
scales depends on several factors: the noise level present in the image material,
the prior distribution of the different types of segments, the class-conditional
distributions associated with each type of segment as well as the actual size of
the (connected) segments. We analyse, theoretically and through experiments,
the possibility of using the overall and class-conditional error rates as criteria
for selecting the optimal sampling of the linear and morphological scale spaces.
It is shown that the overall error rate is optimised by taking the prior class
distribution in the image material into account. However, a uniform (ignorant)
prior distribution ensures constant class-conditional error rates. Consequently,
we advocate for a uniform prior class distribution when an uncommitted, scaleinvariant
segmentation approach is desired.
Experiments with a neural net classifier developed for segmentation of
dynamic MR images, acquired with a paramagnetic tracer, support the
theoretical results. Furthermore, the experiments show that the addition of
spatial features to the classifier, extracted from the linear or morphological
scale spaces, improves the segmentation result compared to a signal-driven
approach based solely on the dynamic MR signal. The segmentation results
obtained from the two types of features are compared using two novel quality
measures that characterise spatial properties of labelled images
Sagittal abdominal diameter: no advantage compared with other anthropometric measures as a correlate of components of the metabolic syndrome in elderly from the Hoorn Study.
BACKGROUND: The sagittal abdominal diameter has been proposed as a useful measure by which to estimate abdominal obesity and as being more strongly related to components of the metabolic syndrome than are other anthropometric measures. OBJECTIVE: The objective was to study which anthropometric measure (ie, sagittal abdominal diameter, waist circumference, waist-to-hip ratio, waist-to-height ratio, or body mass index) is the strongest correlate of components of the metabolic syndrome (ie, glucose and lipid concentrations and blood pressure) in the elderly. DESIGN: The Hoorn Study is a population-based cohort study in older Dutch men and women. Cross-sectional data were analyzed. Age-adjusted Pearson correlations of anthropometric measures with components of the metabolic syndrome were calculated in 826 subjects (389 men, 437 women) aged 56-83 y. Analyses were performed with adjustment for age and stratification for sex and age (/=65 y). RESULTS: No single anthropometric measure was consistently correlated more strongly with components of the metabolic syndrome than were the other measures in either men or women. The associations were generally stronger in younger subjects than in older subjects and in women than in men. For example, the correlation between sagittal abdominal diameter and postload glucose was 0.35 (P < 0.001) in younger and 0.14 (P = 0.051) in older men, and the correlation between waist circumference and postload glucose was 0.33 (P < 0.001) in older women and 0.14 (P = 0.062) in older men. CONCLUSION: The use of sagittal abdominal diameter has no advantages over simpler and more commonly used anthropometric measures such as the waist circumference in older men and women
-Spectral theory of locally symmetric spaces with -rank one
We study the -spectrum of the Laplace-Beltrami operator on certain
complete locally symmetric spaces with finite volume and
arithmetic fundamental group whose universal covering is a
symmetric space of non-compact type. We also show, how the obtained results for
locally symmetric spaces can be generalized to manifolds with cusps of rank
one
Observation of Scaling Violations in Scaled Momentum Distributions at HERA
Charged particle production has been measured in deep inelastic scattering
(DIS) events over a large range of and using the ZEUS detector. The
evolution of the scaled momentum, , with in the range 10 to 1280
, has been investigated in the current fragmentation region of the Breit
frame. The results show clear evidence, in a single experiment, for scaling
violations in scaled momenta as a function of .Comment: 21 pages including 4 figures, to be published in Physics Letters B.
Two references adde
Parallel computation of 3-D soil-structure interaction in time domain with a coupled FEM/SBFEM approach
The final publication is available at Springer via http://dx.doi.org/10.1007/s10915-011-9551-xThis paper introduces a parallel algorithm for the scaled boundary finite element method (SBFEM). The application code is designed to run on clusters of computers, and it enables the analysis of large-scale soil-structure-interaction problems, where an unbounded domain has to fulfill the radiation condition for wave propagation to infinity. The main focus of the paper is on the mathematical description and numerical implementation of the SBFEM. In particular, we describe in detail the algorithm to compute the acceleration unit impulse response matrices used in the SBFEM as well as the solvers for the Riccati and Lyapunov equations. Finally, two test cases validate the new code, illustrating the numerical accuracy of the results and the parallel performances. © Springer Science+Business Media, LLC 2011.Jose E. Roman and Enrique S. Quintana-Orti were partially supported by the Spanish Ministerio de Ciencia e Innovacion under grants TIN2009-07519, and TIN2008-06570-C04-01, respectively.Schauer, M.; RomĂĄn MoltĂł, JE.; Quintana Orti, ES.; Langer, S. (2012). Parallel computation of 3-D soil-structure interaction in time domain with a coupled FEM/SBFEM approach. Journal of Scientific Computing. 52(2):446-467. doi:10.1007/s10915-011-9551-xS446467522Anderson, E., Bai, Z., Bischof, C., Demmel, J., Dongarra, J., Croz, J.D., Greenbaum, A., Hammarling, S., McKenney, A., Sorensen, D.: LAPACK Userâs Guide. Society for Industrial and Applied Mathematics, Philadelphia (1992)Antes, H., Spyrakos, C.: Soil-structure interaction. In: Beskos, D., Anagnotopoulos, S. (eds.) Computer Analysis and Design of Earthquake Resistant Structures, p. 271. Computational Mechanics Publications, Southampton (1997)Appelö, D., Colonius, T.: A high-order super-grid-scale absorbing layer and its application to linear hyperbolic systems. J. Comput. 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A Game-Theoretic approach to Fault Diagnosis of Hybrid Systems
Physical systems can fail. For this reason the problem of identifying and
reacting to faults has received a large attention in the control and computer
science communities. In this paper we study the fault diagnosis problem for
hybrid systems from a game-theoretical point of view. A hybrid system is a
system mixing continuous and discrete behaviours that cannot be faithfully
modeled neither by using a formalism with continuous dynamics only nor by a
formalism including only discrete dynamics. We use the well known framework of
hybrid automata for modeling hybrid systems, and we define a Fault Diagnosis
Game on them, using two players: the environment and the diagnoser. The
environment controls the evolution of the system and chooses whether and when a
fault occurs. The diagnoser observes the external behaviour of the system and
announces whether a fault has occurred or not. Existence of a winning strategy
for the diagnoser implies that faults can be detected correctly, while
computing such a winning strategy corresponds to implement a diagnoser for the
system. We will show how to determine the existence of a winning strategy, and
how to compute it, for some decidable classes of hybrid automata like o-minimal
hybrid automata.Comment: In Proceedings GandALF 2011, arXiv:1106.081
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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