Titel Deelnemers "Korte inhoud" "Multi-Physical Time- and Frequency-Domain Fault Detection and Isolation Technique for Power-Electronic Converters in DFIG Wind Turbines" "Marcelo Nesci Soares, Yves Mollet, Michel Kinnaert, Johan Gyselinck, Jan Helsen" "A multi-physical time- and frequency-domain fault detection and isolation (FDI) method for power-electronic converters (PECs) of wind turbines is presented in this paper, with focus on open-circuit faults and the doubly-fed induction generator (DFIG) drivetrain topology. In order to reduce the risk of false alarms, the proposed approach combines fault indicators based on time- and frequency-domain analysis of the electrical signals, as well as frequency-domain analysis of vibration signals. The effectiveness of the method is illustrated on test bench data recorded in different healthy and faulty operating modes." "Loss minimisation strategy for DFIG in wind turbine considering iron losses" "Johan Gyselinck, Yves Mollet, Luis Guilherme Barbosa Rolim" "Nowadays doubly fed induction generator (DFIG) is the mainly used generator in wind power generation, and several efforts are being made to tackle the issues related to their high production costs. In order to solve this problem, this work presents an optimized control strategy that seeks to mitigate the electrical losses inside the generator. The control strategy is based on the optimal reactive power sharing between the rotor and stator circuits of the generator connected to a back-to-back power electronic converter (PEC). In this paper the iron losses, which are traditionally ignored in machine models and vector controls, are considered to achieve better performance. Moreover, since the loss minimisation strategy requires different converter operation points, a numerical model for calculating the semiconductor power losses is shown to evaluate whether this strategy compromises the system losses. Simulation results for a 7.5 kW DFIG show the amount of power saved when the loss minimisation control is applied." "Robust Power-Electronic-Converter Fault Detection and Isolation Technique for DFIG Wind Turbines" "Yves Mollet, Johan Gyselinck, Michel Kinnaert" "This paper proposes a robust fault detection and isolation (FDI) technique for the power electronic converter (PEC) of doubly-fed induction generator (DFIG) wind turbines (WTs), and in particular for open-circuit faults herein. It combines fault indicators based on the processing of the Clarke transformation of the converter currents and a statistical change detection algorithm, namely a cumulative sum (CUSUM) algorithm that detects significant changes in the variance of the reactive power. This allows for a reduction of the false alarm rate compared to an approach relying exclusively on the current analysis. The proposed FDI technique is validated by means of both simulation and experimental results." "Vibration-Based Rotor-Side-Converter Open-Switch-Fault Detection in DFIGs for Wind Turbines" "Johan Gyselinck, Nicoletta Gioia" "Due to the strong growth of wind power in the energy mix and the intense development of higher-power wind turbines, reducing the operating and maintenance costs has become a crucial aspect nowadays to guarantee the security of electricity supply. Condition monitoring plays a key role in achieving this goal. Today most monitoring strategies for converters focus on monitoring the electrical parameters of the converter and on temperature monitoring of the insulated-gate bipolar transistors (IGBTs) in a direct or more indirect way. This paper proposes an alternative approach. Vibration measurements performed on the doubly fed induction generator (DFIG) connected to the converter are used to detect the converter IGBT problems. We focus on the open-switch fault in the rotor side converter (RSC) to illustrate this concept. Spectral analysis is done on the measured vibrations to detect this type of faults. First, the approach is illustrated by means of a simulation model representing a 3 kW DFIG wind turbine test bench. In a second step, the approach is validated on the corresponding bench. A differentiation is made between sub-synchronous and super-synchronous rotation speeds. The ability of the method to detect the fault in both conditions is shown." "Coevolution of reproductive characteristics in three dioecious fig species and their pollinator wasps" "Wen-Juan Ma, Yan Q. Peng, Da-R Yang, Jun M. Guan" "This study investigates dioecious fig species using a pollinator introduction experiment. Our aims were to determine: (1) whether there was a significant difference in foundress distribution between sexes per fig species; (2) whether fig size and foundress number affect reproductive success of dioecious figs; and (3) who is the ‘controlling partner’ in the fig/pollinator mutualism. Three dioecious fig species: Ficus semicordata, Ficus hispida and Ficus tinctoria from Xishuangbanna, China, were selected for this experiment. We found that there was no significant difference of the foundress number in female and male figs of F. semicordata, F. hispida and F. tinctoria. Also, the foundress number did not depend on the fig diameter. The numbers and the proportions of fig seeds and female wasp offspring significantly increased with more foundresses; and fig seed number was significantly higher than female wasp offspring in F. semicordata and F. hispida, but not in F. tinctoria. Our results indicate that figs are generally the ‘controlling partner’ in fig-wasp mutualisms in species with large figs, but not with small figs. Compared with published studies of reproductive success in monoecious figs, the dioecious figs seem to be more efficient in producing both seeds and wasp offspring when there is a high number of foundress." "Why and How to Dig into Plant Metabolite-Protein Interactions." "Venegas-Molina Jhon, Molina-Hidalgo Francisco, Elke Clicque, Alain Goossens" "De criminibus (ad lib. xlvii et xlviii Dig. commentarivs), 1644, Antonius Matthaeus (II) (1601-1654)" "Georges Martyn" "’Gå och pensionera dig!’ A comparative, corpus-based study of the Swedish verb ’att gå’ and the Dutch verb ’gaan’ with special emphasis on ingressive and future marking" "Martje Wijers" "This paper will give an account of two seemingly equivalent verbs: Swedish 'gå' and Dutch 'gaan' and will focus principally on the way these verbs can be used in constructions with ingressive and future-directed meaning. One of the more significant findings to emerge from this study is that the two verbs are used similarly in a surprisingly small part of the studied material. It was also shown that this was often caused by other reasons than the fact that the Swedish verb has a more specific meaning than Dutch gaan that can function as a auxiliary to express future." "Access to documents relating to EU competition and state aid cases pursuant to regulation 1049/2001: towards a rebuttable presumption as a 'Fig Leaf' for intransparency?" "O. Brouwer, Jan Blockx" "Early Old Kingdom rock circle cemeteries in Deir el-Bersha and Deir Abu Hinnis" "Bart Vanthuyne" "Since 2002 the Deir el-Bersha Project has been investigating several cemetery and settlement sites at Deir el-Bersha and the surrounding region. In 2009 excavations started in the early Old Kingdom cemetery, located primarily on the escarpment north of the Wadi Nakhla, and this work has already yielded surprising results. The cemetery not only turned out to be very large but also contained many hundreds of burials. The methods of burial in fact continue a tradition already well established in the preceding dynasties, i.e., adults and children were interred in or under a variety of burial containers. However, new is that this container was mainly placed directly on the bedrock and surrounded and covered up by many stones and boulders, thus forming the so-called rock circle tomb. The author also discovered similar tombs in Deir Abu Hinnis, just north of Deir el-Bersha, whilst it was already known that in Nuwayrat a similar contemporary rock circle cemetery existed. A preliminary report on the work in the rock circle cemeteries in Deir el-Bersha and Deir Abu Hinnis is presented, in which a selection of tombs is illustrated and some initial results described. Thus, it will become clear that this type of tomb was actually common in this part of Middle Egypt."