A new method of excitation control based on fuzzy set theory

The synthesis of the structure of the power system stabiliser (PSS) and its parametrization are based entirely on methods of linear system theory. Thus the desired effect of the PSS is limited to a bounded area around one system operating point. The use of a controller based on fuzzy set theory introduces an event controlled excitation of the synchronous machine taking into account the power system operation. The desired response of the fuzzy controller is given by a set of rules which are obtained from the limits of the voltage regulator and the undesired performance of the conventional excitation control. A fuzzy controller has been developed for which simulation results are provided. These results support the concept of a fuzzy controller for the purpose of excitation control. They show that a well designed fuzzy controller is superior to a fast excitation control with an additional PSS     

A hybrid ASM approach for sparse volumetric data segmentation

Three-Dimensional (3D) Active Shape Modeling (ASM) is a straightforward extension of 2D ASM. 3D ASM is robust when true volumetric data is considered. However, when the information in one dimension is sparse, pure 3D ASM tends to be less robust. We present a hybrid 2D + 3D methodology which can deal with sparse 3D data. 2D and 3D ASMs are combined to obtain a “global optimal” segmentation of the 3D object embedded in the data set, rather than the “locally optimal” segmentation on separate slices. Experimental results indicate that the developed approach shows equivalent precision on separate slices but higher consistency for whole volumes when compared to 2D ASM, while the results for whole volumes are improved when compared to the pure 3D ASM approach. The text was submitted by the authors in English. Stuart Michael Williams, born in 1967, graduated with BAHons in 1989, BMBCh in 1992 from Oxford University, UK; MRCP (1995), FRCR(1999); Stuart Michael Williams is currently the Consultant Radiologist of Norfolk and Norwich University Hospital, Norwich, UK. His research areas include oncological radiology with an interest in image analysis and medical education. Stuart Michael Williams has 24 publications (monographs and articles). He is a member of the Royal College of Radiologists; member of the European Congress of Radiology; and a member of the European Society of Magnetic Resonance in Medicine and Biology. Yanong Zhu, born in 1975, graduated with B. Sci. in 1997 and M. Sci. in 2002 from Northwest University, China and PhD in 2006 from the University of East Anglia, Norwich, UK. His research areas include computer vision, medical image understanding, and analysis. Yanong Zhu has eight publications (monographs and articles). Reyer Zwiggelaar, born in 1963, graduated with B. Sci. from State University Groningen, the Netherlands in 1989. He was awarded his PhD in 1993 by University College London, UK. Reyer Zwiggelaar is currently the Senior Lecturer at the University of Wales Aberystwyth, UK. Dr. Zwiggelaar has more than 80 publications (monographs and articles). His research areas include medical image understanding, especially concentrating on mammographic data, pattern recognition, statistical methods, and feature detection techniques.     

Selective improvement of porcine fat firmness by a diet enriched in medium-chain fatty acids

The effects of 4% fat either rich in medium-chain fatty acids (MCFA; saturated fat) or in polyenoic fatty acids (PUFA; unsaturated fat) isoenergetically exchanging carbohydrates of a low-fat diet (control) on performance and product quality were evaluated with 180 growing pigs. Growth, carcass and meat quality were not affected by the fat treatments. Although elevated in blood serum, cholesterol was not increased in belly meat when the MCFA-rich diet was fed. Fatty acid composition of backfat reflected dietary fat composition. The significantly lowest shelf life and melting temperatures were found with the unsaturated-fat diet. When compared with control, fat tissue PUFA contents were slightly higher in the saturated-fat diet, and fat melting temperatures were somewhat lower. In contrast, the use of this MCFA-enriched diet increased penetrometer firmness in pure 4°C temperated backfat by more than 50% as compared with control and to about the tenfold level of the firmness obtained in the unsaturated-fat diet. Impression of flavour and odor in lean and fatty meat were not systematically affected by the diets. The present results show a high potential of MCFA-enriched diets to selectively increase fat firmness in pigs without greater undesired side effects on other traits of product quality.     

Evaluation of SRD1000 Superconductive Reference Devices

No Heading Recently, a superconductive reference device, SRD1000, with ten reference materials has been developed to enable simplified in situ calibration of interpolating thermometers. We report on the evaluation of SRD1000 prototypes at various laboratories. The devices were built and tested by HDL and KOL, calibrated at NMi-VSL and then distributed to other partners where they were re-calibrated against the local realisations of the PLTS-2000 or laboratory scales. As a result, we obtained data on the superconductive transition temperatures, widths and shapes for four different devices. Reproducibility, sharpness of the transitions, supercooling and sensitivity to magnetic fields are evaluated. This leads to estimates of the uncertainty in determination of the transition midpoint and temperature.PACS numbers: 07.20.Dt, 07.20.Mc, 74.62.–c, 74.70.Ad     

Zur Tragfähigkeit von Nägeln im Hirnholz unter Abscherbelastung

Systematic studies were carried out to investigate the load bearing capacity of nails in end grain steel plating of laminated wooden beams. From the results suggestions for minimum nail distances and for dimensions are discussed. According to these results, the load bearing capacity of nails in end grain appear to be satisfactory.     

Morphology and Growth Kinetics of 3He Crystals Below 1 mK

The shapes as well as the growth and melting properties of bcc-³He single crystals have been investigated with a low temperature Fabry-Pérot interferometer. Eleven types of facets were clearly identified during slow crystal growth at the temperature of 0.55 mK, where the solid is in the antiferromagnetically ordered u2d2 phase. The growth rates of the individual facets have been measured and the results indicate significant growth anisotropy. The observed linear dependence of the growth velocity on the driving force shows that facets grow due to the presence of screw dislocations, while the step velocity is limited by the spin wave velocity due to the strong interaction of the moving step with magnons in the solid. The measured growth rates of the facets and the assumed growth mechanism gave us the unique opportunity to obtain the step free energies for ten different types of facets observed during a single growth sequence. The dependence of the free energy of the step on the step height is compared with predictions of the weak- and strong-coupling models. Our results suggest that ³He crystals have rather strong coupling of the liquid/solid interface to the crystal lattice and that the step-step interactions are of elastic origin.     

Zur Tragfahigkeit von Nageln im Hirnholz unter Belastung auf Herausziehen and unter kombinierter Belastung (Herausziehen and Abscheren)

This article describes a systematic study of the load bearing capacity of nails in end grain steel plating of laminated wooden beams. Investigated are the bearing capacities under withdrawal load and under combined loading (shear and withdrawal forces).     

Observation of3He crystal nucleation from the superfluid phases

A CCD camera operating at T = 65 K was mounted in the vacuum space of our nuclear demagnetization cryostat. This has allowed us to make observations of³He crystals at temperatures below the superfluid phase transitions, in contrast to direct optical observations, which have so far been limited to T 20 mK.1 The good thermal equilibrium provided by the superfluid allows us to nucleate single crystals of³He in the region of the cell visible to the optical system. This occurs either spontaneously (due either to gravitational pressure gradients or local surface defects) or as a result of a small applied heat pulse.     

Tendenzen des Tragverhaltens von Anschlüssen mit Nägeln und Schrauben in Kurz- und Langzeitversuchen mit Stahlblechen und BFU-Platten im Hirnholz

Kürzlich wurde ausführlich über Hirnholz-Stahlblech-Nagelanschlüsse an Bretschichtholzquerschnitte (BSH-Querschnitte) unter reiner Abscherbelastung sowie unter Ausziehbelastung und unter kombinierter Beanspruchung (Abscheren und Herausziehen) berichtet. Der vorliegende Beitrag beschäftigt sich mit Zusatzversuchen, die im Sinne von Tastversuchen durchgeführt wurden. Es werden Tendenzen des Tragverhaltens unter Abscherbelastung aufgezeigt für Hirnholz-Anschlüsse von Bau-Furniersperrholzplatten (BFU-Platten) mit Nägeln (mit und ohne Vorbohrung) und Schrauben (vorgebohrt) an BSH, von Stahlblechen mit Nägeln an Vollholz und von Schrauben an BSH. Darüber hinaus wurden aus Vergleichsgründen Nagel-Stahlblech-Anschlüsse an BSH-Seitenholz und zur Ermittlung des Langzeit-Verformungsverhaltens Langzeit-Versuche mit Stahlblech-Anschlüssen mit Nägeln an BSH-Hirn- und Seitenholz durchgeführt.