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Better Robustness (good + robustness)

Distribution by Scientific Domains

Engineering	60%

Selected Abstracts

Groupwise registration based on hierarchical image clustering and atlas synthesis

HUMAN BRAIN MAPPING, Issue 8 2010
Qian Wang
Abstract Groupwise registration has recently been proposed for simultaneous and consistent registration of all images in a group. Since many deformation parameters need to be optimized for each image under registration, the number of images that can be effectively handled by conventional groupwise registration methods is limited. Moreover, the robustness of registration is at stake due to significant intersubject variability. To overcome these problems, we present a groupwise registration framework, which is based on a hierarchical image clustering and atlas synthesis strategy. The basic idea is to decompose a large-scale groupwise registration problem into a series of small-scale problems, each of which is relatively easy to solve using a general computer. In particular, we employ a method called affinity propagation, which is designed for fast and robust clustering, to hierarchically cluster images into a pyramid of classes. Intraclass registration is then performed to register all images within individual classes, resulting in a representative center image for each class. These center images of different classes are further registered, from the bottom to the top in the pyramid. Once the registration reaches the summit of the pyramid, a single center image, or an atlas, is synthesized. Utilizing this strategy, we can efficiently and effectively register a large image group, construct their atlas, and, at the same time, establish shape correspondences between each image and the atlas. We have evaluated our framework using real and simulated data, and the results indicate that our framework achieves better robustness and registration accuracy compared to conventional methods. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc. [source]

Image matching based on relation between pixels located on the maximum and minimum gray-levels in local area

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 2 2007
Fumihiko Saitoh Member
Abstract This paper proposes a template matching method maximum and minimum gray levels pixels sign matching (MMM) which is based on a comparison of the gray levels of a pair of pixels whose locations are on the pixels with the maximum and the minimum gray levels in a local area in a template image. In this method, the locations of the pixels with the maximum and the minimum gray levels are registered in a local area whose center is every pixel in a template image. The target image area is searched from the matching ratio which is obtained by the relation between the gray levels of the two pixels whose locations have been registered in the template image. The experimental results show that the proposed method had equal or better robustness to the inferior factors of objective images in comparison with the three typical conventional template matching methods. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

Pressure and temperature-based adaptive observer of air charge for turbocharged diesel engines

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2004
A. G. Stefanopoulou
Abstract In this paper we design an adaptive air charge estimator for turbocharged diesel engines using intake manifold pressure, temperature and engine speed measurements. This adaptive observer scheme does not depend on mass air flow sensors and can be applied to diesel engines with no exhaust gas recirculation (EGR). The performance of the adaptive scheme is shown in simulations to be comparable to conventional air charge estimation schemes if perfect temperature measurements are available. The designed scheme cannot estimate fast transients and its performance deteriorates with temperature sensor lags. Despite all these difficulties, this paper demonstrates that (i) the proposed scheme has better robustness to modelling errors because it provides a closed-loop observer design, and (ii) robust air charge estimation is achievable even without air flow sensors if good (fast) temperature sensors become available. Finally, we provide a rigorous proof and present the implementation challenges as well as the limiting factors of this adaptation scheme and point to hardware and temperature sensor requirements. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Adaptive AQM controllers for IP routers with a heuristic monitor on TCP flows

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2006
Yang Hong
Abstract We propose adaptive proportional (P) and proportional-integral (PI) controllers for Active Queue Management (AQM) in the Internet. We apply the classical control theory in the controller design and choose a proper phase margin to achieve good performance of AQM. We have identified a simple heuristic parameter that can monitor the changes of network environment. Our adaptive controllers would self-tune only when the dramatic change in the network parameters drift the monitoring parameter outside its specified interval. When compared to P controller, a PI controller has the advantage of regulating the TCP source window size by adjusting the packet drop probability based on the knowledge of instantaneous queue size, thus steadying the queue size around a target buffer occupancy. We have verified our controllers by OPNET simulation, and shown that with an adaptive PI controller applied, the network is asymptotically stable with good robustness. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Testing for the Presence of Self-Similarity of Gaussian Time Series Having Stationary Increments

JOURNAL OF TIME SERIES ANALYSIS, Issue 5 2000
Jean-Marc Bardet
A method for testing for the presence of self-similarity of a Gaussian time series with stationary increments is presented. The test is based on estimation of the distance between the time series and a set of time series containing all the fractional Brownian motions. This distance is constructed from two estimations of multiscale generalized quadratic variations expectations. The second one requires regression estimates of the self-similarity index H. Two estimations of H are then introduced. They present good robustness and computing time properties compared with the Whittle approach, with nearly similar convergence rate. The test is applied on simulated and real data. The self-similarity assumption is notably accepted for the famous Nile River data. [source]