다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Statistics for Spatial Data.

The purpose of this paper is to provide a comprehensive presentation and interpretation of the Ensemble Kalman Filter (EnKF) and its numerical implementation. The EnKF has a large user group, and numerous publications have discussed applications and theoretical aspects of it. This paper reviews the important results from these studies and also presents new ideas and alternative interpretations which further explain the success of the EnKF. In addition to providing the theoretical framework needed for using the EnKF, there is also a focus on the algorithmic formulation and optimal numerical implementation. A program listing is given for some of the key subroutines. The paper also touches upon specific issues such as the use of nonlinear measurements, in situ profiles of temperature and salinity, and data which are available with high frequency in time. An ensemble based optimal interpolation (EnOI) scheme is presented as a cost-effective approach which may serve as an alternative to the EnKF in some applications. A fairly extensive discussion is devoted to the use of time correlated model errors and the estimation of model bias.

The Ensemble Kalman Filter: Theoretical formulation and practical implementation

Adaptive sparse polynomial chaos expansion based on least angle regression

To improve the performance of particle image velocimetry in measuring instantaneous velocity fields, direct cross-correlation of image fields can be used in place of auto-correlation methods of interrogation of double- or multiple-exposure recordings. With improved speed of photographic recording and increased resolution of video array detectors, cross-correlation methods of interrogation of successive single-exposure frames can be used to measure the separation of pairs of particle images between successive frames. By knowing the extent of image shifting used in a multiple-exposure and by a priori knowledge of the mean flow-field, the cross-correlation of different sized interrogation spots with known separation can be optimized in terms of spatial resolution, detection rate, accuracy and reliability.

Theory of cross-correlation analysis of PIV images : Image analysis as measuring technique in flows

An unsteady adaptive stochastic finite elements formulation for rigid-body fluid-structure interaction

Speeding up Kriging through fast estimation of the hyperparameters in the frequency-domain

Adaptive radial basis function mesh deformation using data reduction

The numerical simulation of an insect-sized 'X-wing' type biplane flapping wing configuration is performed in 3D using an immersed boundary method solver at Reynolds numbers equal to 1000 (1 k) and 5 k, based on the wing's root chord length This X-wing type flapping configuration draws its inspiration from Delfly, a bio-inspired ornithopter MAV which has two pairs of wings flapping in anti-phase in a biplane configuration The objective of the present investigation is to assess the aerodynamic performance when the original Delfly flapping wing micro-aerial vehicle (FMAV) is reduced to the size of an insect Results show that the X-wing configuration gives more than twice the average thrust compared with only flapping the upper pair of wings of the X-wing However, the X-wing's average thrust is only 40% that of the upper wing flapping at twice the stroke angle Despite this, the increased stability which results from the smaller lift and moment variation of the X-wing configuration makes it more suited for sharp image capture and recognition These advantages make the X-wing configuration an attractive alternative design for insect-sized FMAVS compared to the single wing configuration In the Reynolds number comparison, the vorticity iso-surface plot at a Reynolds number of 5 k revealed smaller, finer vortical structures compared to the simulation at 1 k, due to vortices' breakup In comparison, the force output difference is much smaller between Re = 1 k and 5 k Increasing the body inclination angle generates a uniform leading edge vortex instead of a conical one along the wingspan, giving higher lift Understanding the force variation as the body inclination angle increases will allow FMAV designers to optimize the thrust and lift ratio for higher efficiency under different operational requirements Lastly, increasing the spanwise flexibility of the wings increases the thrust slightly but decreases the efficiency The thrust result is similar to one of the spanwise studies, but the efficiency result contradicts it, indicating that other flapping parameters are involved as well Results from this study provide a deeper understanding of the underlying aerodynamics of the X-wing type, which will help to improve the performance of insect-sized FMAVs using this unique configuration

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Hester Bijl

Papers

An unsteady adaptive stochastic finite elements formulation for rigid-body fluid-structure interaction

Speeding up Kriging through fast estimation of the hyperparameters in the frequency-domain

Adaptive radial basis function mesh deformation using data reduction

Numerical simulation of X-wing type biplane flapping wings in 3D using the immersed boundary method.

Fast unsteady flow computations with a Jacobian-free Newton-Krylov algorithm