496 research outputs found
The Quenast plug: a mega-porphyroclast during the Brabantian orogeny (Senne valley, Brabant massif)
No full textIn the fine-grained Ordovician siliciclastic deposit surrounding the Quenast plug, a variety of structural features demonstrate that the Quenast plug was emplaced prior to the Brabantian deformation event. These features include: a) a large-scale bending of the cleavage, mimicking the shape of the plug; b) a concomitant change in the orientation of the transverse fractures; c) a marked variation in cleavage intensity around the plug, with a high-strain zone along the NE-side of the plug and a low-strain zone along the NW-side of the plug; d) contractional and dilational kink bands. In combination with the ellipsoidal cross-section of the plug, these features indicate that the Quenast plug can be regarded as having acted as a mega-porphyroclast during the Brabantian deformation event. The different structural features are discussed and related to the geometry and deformation of the Quenast plug. Also the temporal and spatial relationships of the Quenast plug with respect to the Asquempont Detachment System and the Nieuwpoort-Asquempont Fault Zone are discussed. Finally, a preliminary attempt is made at estimating the shortening across the plug. Future work, concentrating on the magnetic fabric within the plug, will shed further light on the behaviour of the plug during the Brabantian deformation event.sponsorship: We kindly acknowledge L. Andre and J. Belliere for thoroughly reviewing the manuscript. We would like to express our gratitude to A. Vergari and M. Lauwers (Gralex), for the permission to access the quarry, their hospitality and enthousiasm. We Would also like to thank A. Herbosch for the helpful field discussions concerning the lithostratigraphical position of the Middle and Upper Ordovician units encountered. T.N. Debacker is a Postdoctoral Fellow of the Fund for Scientific Research-Flanders (F.W.O.-Vlaanderen) and M. Sintubin is a Research Associate of the "Onderzoeksfonds, K.U.Leuven". This work fits into the research projects G.0274.99, G.0094.01 and G.0271.05 of the F.W.O.-Vlaanderen. (F.W.O.-Vlaanderen|G.0274.99, F.W.O.-Vlaanderen|G.0094.01, F.W.O.-Vlaanderen|G.0271.05)status: Publishe
On the use of magnetic techniques for stratigraphic purposes: examples from the Lower Palaeozoic Anglo-Brabant Deformation Belt (Belgium)
No full textWithin the Lower Palaeozoic Anglo-Brabant Deformation Belt, magnetic susceptibility on its own does not allow for a straightforward distinction between different lithostratigraphic units, except for the high-susceptibility levels of the Lower Cambrian Tubize Formation. Moreover, the variation in magnetic susceptibility within individual lithostratigraphic units is often larger than that between different units, but at the same time, this internal variation in susceptibility may show no clear relationship to features obvious in outcrop or hand specimens. Hence, the applicability of magnetic susceptibility for stratigraphic purposes in the Anglo-Brabant Deformation Belt is low. Better results are obtained using the temperature-dependent variation in terms of percentage of magnetic susceptibility within the "room temperature interval". Also the anisotropy of magnetic susceptibility allows for a better distinction between different lithostratigraphic units than does magnetic susceptibility. The best results are obtained by a comparison of thermal demagnetisation curves of magnetic remanence, used for determining ferromagnetic mineralogy. This method even allows distinguishing lithostratigraphic units in which ferromagnetic carriers do not contribute to overall magnetic susceptibility and its anisotropy. Ideally, each magnetic technique should be used for stratigraphic purposes only in combination with other magnetic techniques. Moreover, knowledge about the magnetic carriers (s.l.) facilitates this use of magnetic techniques and strongly improves the accuracy of the interpretations.sponsorship: We would like to thank F. Martin-Hernandez and O. Averbush for thoroughly reviewing the manuscript. We are very grateful to A. Flirt (ETH, Zurich, Switzerland) for the additional magnetic analyses by means of the Curie Balance and to C. Aubourg for the stimulating discussions on ferromagnetic mineralogy. We would also like to acknowledge A. Herbosch for pointing out the unexpected lithology at Braine-le-Chateau. T.N. Debacker is a Postdoctoral Fellow of the Research Foundation-Flanders (F.W.O.-Vlaanderen). This work forms part of research project G.0271.05 of the F.W.O.-Vlaanderen. The handheld magnetic susceptibility meter was obtained by means of extra research funds given by the F.W.O.-Vlaanderen to T. Debacker. (F.W.O.-Vlaanderen|G.0271.05)status: Publishe
Naucnaja diglossija v istoriceskom obrazovanii Aleksandra II (Lekcii o Petre Velikom)
No full textThe article focuse on the historical education of the Tsar Alexander II with a particular attention to the field of Russian History and the role of Peter the Great. The author analyzes the different scientific languages and approaches used by his teachers in teachin Russian history and their interaction
Testing and analysis of axial gap permanent magnet DC motors
No full textThis thesis is concerned primarily with the testing and analysis of design variations of the Lynch motor, which is an axial gap permanent magnet dc machine. These variants include: a standard production motor, a motor with low iron volume, a motor with bigger area of magnets and a motor using powder iron instead of laminations. The powder iron motor was constructed by the author, while all the other motors were provided by the Lynch Motor Company.Tests were conducted to evaluate motor circuit parameters, losses and efficiency using a purpose built test rig which was built in the first stage of the project. Finite element analysis (FEA) was used to determine the levels of the magnetic saturation in the different motors and calculate torque, inductance and EMF. The FEA was also used as bases for comparison with analytical electromagnetic calculations. A dynamic circuit model, whose parametric were derived from FEA and analytical calculations validated by test, was also constructed to study the effect of brush thickness on circulating current and torque production.The results of the work revealed that the larger magnet motor has a high level of saturation resulting in a higher slope of the torque-speed curve. The lower iron volume motor and the powder iron cored motor produced less torque and have less flux density than the standard Lynch motor. The test results proved that the selected powder iron material is usable in the Lynch rotated armature but it still needs improvements to close the performance gap with laminations. The powder iron motor has back emf that is 10% lower than the standard motor, and consequently a lower efficiency.The results show that performance of the Lynch motor can be improved by optimising the size of the saturated parts of the motor, which are the stator discs and the armature teeth. In addition, careful selection of brush number, geometry and type can improve the motor performance.An alternative single gap motor was also studied. The test results show that it has more armature reaction than the dual gap motor and therefore it produced less torque with less efficiency
Contractional kink bands formed by stress deflection along pre-existing anisotropies? Examples from the Anglo-Brabant Deformation Belt (Belgium) and the North Dobrogea Orogen (Romania)
No full textKink bands within two slate belts, the Anglo-Brabant Deformation Belt (Belgium) and the North Dobrogea Orogen (Romania), reveal similar problems with respect to linking kink band geometries to expected palaeostress directions. In the North Dobrogea Orogen, the two opposite kink band sets of two different systems of conjugate kink bands develop for a wide variety of cleavage orientations. In the Anglo-Brabant Deformation Belt, the occurrence of the two opposite kink band sets of a conjugate kink band system opposes the expected occurrence. In both cases, this can be attributed to stress deflection along a pre-existing anisotropy. Moreover, the presence of kink bands in the North Dobrogea Orogen with curving kink axes (and curving kink band boundaries) also puts doubt on the direct relationship between kink band geometry and stress. The idea of stress deflection along a pre-existing anisotropy and the strong control of the pre-existing anisotropy on the kink band geometry and orientation has important implications for the use of kink bands as regional palaeostress indicators. Depending on the relative intensity and relative orientation of the pre-existing fabrics (here bedding and cleavage), different mechanisms of kink band development may operate. Depending on the mechanism, different solutions in terms of inferred palaeostress direction may exist. © 2008 Elsevier Ltd. All rights reserved.sponsorship: The authors wish to acknowledge B. Goscombe, D. Srivastava and T. Blenkinsop for their constructive remarks on the manuscript, and are grateful to G. Oaie and M. Vaida for the support during the fieldwork in North Dobrogea (Romania). T.N. Debacker is a Post-doctoral Fellow of the Fund for Scientific Research-Flanders (F.W.O.-Vlaanderen) and M. Sintubin a Research Associate of the "Onderzoeksfonds, K.U.Leuven". This work, resulting from fieldwork when T. Debacker was at the Katholieke Universiteit Leuven (2002-2005), forms part of research projects G.0274.99, G.0094.01 and C.0271.05 of the F.W.O.-Vlaanderen. The research in Romania benefited from the International scientific and technological cooperation program from the Science, Innovation and Media Department of the Ministry of the Flemish Community (BIL01/34). (Science, Innovation and Media Department of the Ministry of the Flemish Community|BIL01/34)status: Publishe
Rocking Revisited 1. Rocking of a Single Cube on a Breakwater Slope
No full textPrototype single layer armour units on a breakwater slope are observed to break. To predict when breakage occurs, the objective of this research project is to obtain knowledge on, and measurements of the rocking behaviour and failure mode of single layer armour units. A single cube on a breakwater slope is subjected to investigations.
Wave flume tests are conducted, in which rotations of a single cube are measured as a consequence of various hydraulic conditions. The tested parameters are: degree of exposure of cube, wave height, wave steepness and position on slope in relation to the water level. A three-axis accelerometer, which is placed in the cube’s centre, is applied during this Master's Thesis. Furthermore, wave gauges are applied to measure the wave conditions.
For future CFD-modelling, measurements are conducted on water pressures during wave run-up on a non-rotating cube, using a pressure sensor. In addition, wave run-up velocities and the movements of the cube are captured with two cameras
Sustainable conjunctive use of groundwater for additional irrigation
No full textCurrently millions of private wells in the Punjab are pumping groundwater as an additional source for irrigation to compensate for irregular surface water supply. Since the 1990s, most of them are skimming wells that aim to reduce the salinity of the pumped groundwater. However, salinization continues to rise over time, often above acceptable limit, which threatens food production. This thesis aims to develop a solution to make groundwater use for additional irrigation sustainable, i.e., to limit the salinity of pumped water in the long run. Based on a model analysis, it was shown that skimming technologies cannot prevent salinization, irrespective of parameters of subsurface, for which some unique pumping tests were analyzed and geophysical measurements were carried out in the Punjab. Sustainability is sought in balancing both water and salt on the scale of field or farm. Both analytical and numerical models were used to show that the adopted concepts will work.Water ManagementCivil Engineering and Geoscience
Groundwater System Identification through Time Series Analysis
No full textGroundwater, water in the ground. Although it is invisible, it is a vital resource for all terrestrial life (whether direct or indirect). Many processes interact with it. Rain recharges it, as it infiltrates the soil. Plant roots take it up, and their leaves evaporate it. It discharges to rivers and streams, and is abstracted with pumping wells. It is controlled with ditches and drainage means. Such processes and activities leave their traces in the groundwater level fluctuations. Careful analysis of these fluctuations may reveal much of the functioning of systems, and of the effects of individual factors. This is shown by many, but practiced by too few, as traditional time series analysis theory and software are complex. In this thesis, a new method of time series analysis is presented. Its continuous time formulation fits existing physical-hydrologic theory and methods well. It is shown that groundwater level responses generally take the shape of simple distribution functions. This notion, combined with the program Menyanthes that was developed, enable the quick and easy analysis of large numbers of time series. The spatial patterns that emerge in the results of multiple models literally add another dimension to the technique. As time series models are usually accurate also, they may be valuable to every (eco)hydrologist.Water ManagementCivil Engineering and Geoscience
Determination of optimal separation well distance for single borehole ATES systems, in the Netherlands, implementing an an axi-symmetric numerical model
No full textAquifer thermal energy storage (ATES) is a growing technology in the Netherlands. There are two kinds of ATES configurations the doublet and the single borehole ATES (SB-ATES) layout. The limited subsurface space in combination with the lower construction cost and the lower performance of the SB-ATES lead to the need to optimize their design. This master thesis focuses on gaining a better insight in the processes that occur around this configuration. Specifically, how anisotropy influences the efficiency of the design and what the optimal distance between filter screens is, in order to limit the interference between the screens, as it has a negative impact on system performance. To meet these two objectives, an axisymmetric numerical model was developed in a MATLAB environment, using MODFLOW and MT3DMS or SEAWAT groundwater flow and transport simulators. The simulation of heat advection was conducted applying the finite different method (FD method), it was the only method compatible with axial symmetric models that produced consistent results. As the FD method is subjected to numerical dispersion, three different grid resolutions were tested that were the 0.25, 0.50 and 1.00 m, respectively. The finest grid was decided to be used in the elaboration, as it gave the most accurate results compared to larger thickness width grid cells. Capacity test and borehole profile data were used to calibrate the overall vertical anisotropy of the case-studies. The capacity test allowed the calibration of one hydraulic parameter, for which the overall vertical anisotropy was chosen. The Kozeny-Carmen equation was used to calculate the hydraulic conductivity of each soil layer. This overall vertical anisotropy even though was estimated roughly, can be used to determine the presence of overlooked clay layers during the drilling of the borehole (anisotropy >10). A sensitivity analysis was applied to estimate the optimum distance between the filter screens. Three different types of SB-ATES, called GT15xx, GT20xx and GT25xx, were examined separately. The numbers indicate the installed pump capacity in m3/h while their mean and representative screen lengths are 5, 7 and 10m respectively. For the sensitivity analysis, three discharge fractions, Qfrac, were tested with values 0,25, 0.50 and 1.00 and three anisotropy values of 2, 5 and 10, these values are representative for sandy soils. The simulation time was 5 years, which was sufficient to the recommended efficiencies. The results showed that the maximum efficiency is practical independent of system type. The optimum separation distance for an anisotropy of 2 is respectively, 25, 30 and 35 m for Qfrac 0.25, 0.50 and 1.00. The evaluation of the sensitivity analysis was conducted, using real-scale case-studies and taking into account the distribution of conductivities along the layers. The available 18 case-studies were examined in terms of efficiency; it was found that a thin resistance layer between the screens, like a clay or peat layer, influences positively the performance of SB-ATES systems. On the other hands, when there is a high conductive zone between the screens, the efficiency drops. Finally, it was found that temperature induced differences in density and viscosity have a negligible effect on SB-ATES systems, at least with injection temperature differences between warm and cold wells up to 120C.HydrogeologyWater ManagementCivil Engineering and Geoscience
Called Back Onstage: Dramaturgic Analysis, Domestic Social Robots, and Privacy
No full textI argue that social robots installed inside homes produce a novel privacy problem when they invite their users to engage with them. To build my case, I introduce relevant concepts from Erving Goffman’s theory of Dramaturgic Analysis to interpret human-robot interactions. Following Goffman, I posit that we pre-reflectively adjust our behavior to communal expectations and perform as characters when interacting with other people in public. We tend to step into character when we encounter familiar social situations, which, I argue, includes those created by robots that mimic human social behavior. Our homes, ideally, enable us to set aside the characters we play in public to pursue private tasks associated with our well-being, autonomy, and intimate relationships. As such, when domestic social robots elicit social responses from users, they may rob users of time they could otherwise dedicate to valuable private activities—an issue I categorize as a privacy problem.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Ethics & Philosophy of Technolog
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