237 research outputs found
“Intelligent” Cinematography in Pre-Revolutionary Kazan: Role of Professor L.O. Darkshevich in Educational Film Development
No full textThe paper analyzes the development of educational cinematography in Kazan during the period of 1908–1916. The author draws attention to the review written by L.O. Darkshevich (1858–1925), the worldwide famous neuropathologist and professor of the Kazan University, of “Drinking and
Its Consequences” (1913), a scientific and popular film. It is assumed that the critical attitude of the neurosurgeon to the first steps of educational cinematography reflects the desire of this person to use his authority to influence the development of “intelligent cinematography”. Furthermore, the paper provides examples of active use of this type of art for educational purposes. Notably, there was a special scientific and popular cinema theatre in Kazan. The Kazan Society of Public Universities actively used cinematography during lectures. During the First Word War, films were screened for free in hospitals for wounded soldiers of the Kazan region. Scientific cinematography was also supported by the state: film demonstrators were exempt from taxes if charity events were held
Stille oogenblikken. Gedenkboek van het verzet der Delftsche studenten en docenten gedurende de jaren 1940-1945.
No full textVerzetsboek van Delftse studenten gedurende de 2e Wereldoorlog. Bevat geannoteerde voorblad (2006). Op voorblad gedenkplaat naar een ontwerp van prof. L.O. Wenkebach door Paul Huf.Delft University of Technolog
Acceptance-by-Design Elicitation of Social Requirements for Intelligent Infrastructures
No full textEngineering Systems and ServicesTechnology, Policy and Managemen
Algal blooms and Membrane Based Desalination Technology
No full textSeawater desalination is rapidly growing in terms of installed capacity (~80 million m3/day in 2013), plant size and global application. An emerging threat to this technology is the seasonal proliferation of microscopic algae in seawater known as algal blooms. Such blooms have caused operational problems in seawater reverse osmosis (SWRO) plants due to clogging and poor effluent quality of the pre-treatment system which eventually forced the shutdown of the plant to avoid irreversible fouling of downstream SWRO membranes. As more extra large SWRO plants (>500,000 m3/day) are expected to be constructed in the coming years, frequent chemical cleaning (>1/year) of SWRO installations will not be feasible, and more reliable pre-treatment system will be required. To maintain stable operation in SWRO plants during algal bloom periods, pre-treatment using ultrafiltration (UF) membranes has been proposed. This thesis addresses the effect of algal blooms on the operation of UF pre-treatment and SWRO. Experimental investigations demonstrated that marine algal blooms can impact the backwashability of UF and can accelerate biological fouling in RO. However, it is unlikely that algae themselves are the main causes of fouling but rather the transparent exopolymer particles (TEPs) that they produce. To better monitor TEPs, a new method capable of measuring TEP as small as 10 kDa was developed and showed that TEPs can be effectively removed by UF pre-treatment prior to SWRO. This work also demonstrated that although TEPs and other algal-derived material (AOM) are very sticky and can adhere to UF and RO membranes, adhesion can be much stronger on membranes already fouled with AOM. Moreover, a model was developed to predict the accumulation of algal cells in capillary UF membranes which further demonstrated that the role of algal cells in UF fouling is not as significant as that of AOM and TEPs. Overall, this study demonstrates that better analytical methods and tools are essential in elucidating the adverse impacts of algal blooms in seawater on the operation of membrane-based desalination plants (UF-RO). It also highlighted the importance of developing effective pre-treatment processes to remove AOM from the raw water and reduce the membrane fouling potential of the feed water for downstream SWRO membranes.Water ManagementCivil Engineering and Geoscience
Smart Wind Turbine: Analysis and Autonomous Flap
No full textWind turbines convert kinetic energy of the wind into electrical energy. Unfortunately, this process is everything but constant, as the wind source shows large fluctuations with high and low frequencies. This turbulence, together with the wind shear and yawed inflow, excites the turbine structure, thereby driving the loads and the design of turbines in general and blades in particular. In response to this, several control mechanisms have been applied to wind turbines since the generation of stall controlled machines in the 1980s. While collective pitch control was applied first, the control mechanisms have become more localised and act on individual turbine blades, rather than on the rotor as a whole. An advanced control scheme is termed 'smart wind turbine'. These type of wind turbine actively measures vibrations of its blades through a set of distributed sensors throughout the blades and then aims to counteract the vibrations using aerodynamic modifications around the blades' trailing edges close to the tips by means of control surface deflections. This thesis investigates two aspects of the smart rotor concept: the analysis of smart rotors and the design of an autonomous flap concept. For the analysis, a wind turbine analysis tool with special focus on smart rotors and controller implementation has been developed. This code, the Delft University Smart Wind turbine Analysis Tool (DU-SWAT), has been benchmarked not only against conventional wind turbine codes, but a comparison study with the first utility-scale smart rotor experiment, the Sandia National Laboratories Smart Rotor, was performed. The experimentally obtained eigenfrequencies of the test turbine matched closely those of the numerical study. The difference in the first eigenfrequency is 2.7% or 0.1 Hz (4.4 Hz experimentally, 4.5 Hz numerically). A second comparison step was a time domain analysis of the wind turbine response to a step deflection input of the flaps. For the tower response, the frequencies and the amplitudes of the numerical and experimental responses agree very well. For blade vibrations, an increase in damping in the numerical simulations is observed. While for low flap deflection amplitudes, up to 5 degrees, the response amplitude is predicted well. When high step deflections are modelled, the numerical simulations increasingly fail to accurately capture the dynamics of the turbine. In combination with the differences in damping, this leads to the conclusion that vortices, shed from the flap tips, interact with the larger tip vortices, possibly due to the proximity of the flaps to the blade tips. This inaccuracy of high flap deflection angles is however of limited importance, as it was demonstrated that the periodic (1P) load, the most dominant contributor to fatigue damage, could be alleviated effectively even with deflection angles up to 5 degrees. The individual flap controller has been tuned to the NREL 5MW reference turbine and has been used to study both fatigue and extreme loads according to the certification regulations. Failure-free cases were included in the analysis, and loads have been monitored throughout the turbine. The fatigue load reduction of the blade root bending moment of 24\% corresponds well with the findings of previous researchers. Besides this verification, it was also shown that the structural loads increase nowhere in the turbine, with the exception of the blade root torsional moment. Several other loads decrease, for example the tower torsion moments and the bending moments in the turbine shaft. The extreme load reduction is smaller than the fatigue load reduction. Still, the ultimate tip deflection and the ultimate blade root bending moment could be reduced by 7\% and 8\%, respectively. The moments in the tower are also reduced. Besides load alleviation, an additional functionality of the smart rotor was established. The flaps can be used to increase the power production of the turbine by responding to fluctuations in the wind speed and the delays in the adjustment of the rotor speed due to the rotor inertia. An intermediate step of the wind turbine analysis was the development of a suitable structural model. The developed structural dynamics model, which is based on modal equations of motion, is not limited to wind turbine structures, but rather applicable to a broad range of engineering problems concerning structural vibrations. The model closes the gap between modal reductions, which are typically used in linear vibration analysis, and non-linear geometry. For that purpose the structure is segmented and the segments are joined by rigid-body displacements in a co-rotational framework, which introduces geometric non-linearities. This allows modelling of the structural dynamics for large deformations, while maintaining linear stress information of the finite element model of all segments. The basic assumption underlying this approach is that the structural displacement is large, but the strains remain small, which is typically the case for slender structures such as wind turbine blades. The second major topic, which has been addressed in this dissertation, is the physical implementation of a flap system. The described flap system is fully autonomous and is mounted as a free-floating flap, which means that the flap can freely rotate around a hinge axis. The flap is controlled by a trailing edge tab and driven by servo actuators. The flap is mass underbalanced and aeroelastically unstable in interaction with one of the main structural modes. This renders the flap system highly responsive to control inputs, but also to external excitations. When vibrating, the kinetic energy of the flap is converted by electromagnetic harvesters into electric energy. This energy is either stored in a battery or used to power the sensors and the actuators. It was demonstrated that the instability of the flap dramatically increases the amount of harvested energy by, in case of the experiment, a factor of 225 for wind speeds just below and above the flutter speed. The flap system measures the vibrations through accelerometers. When unstable, the vibration amplitude is either limited by structural delimiters or can be actively controlled by the control system. It was shown, that the flap system can be self-sufficient during the controlled limit cycle oscillation. Id est the power produced during limit cycle oscillation is greater than the power consumed to keep the oscillation amplitude constant. The main advantage of the autonomous flap is its improved replaceability compared with non-autonomous ones. As it neither needs a connection to a central control unit and a power system, nor is an integral part of the wind turbine blades like seamless solutions, it can be exchanged easily in case of failure. In conclusion, smart wind turbines have a great potential to improve the cost efficiency by reducing loads for most turbine components as has been shown in this dissertation. This can be achieved using the novel flap concept, which helps, due to its plug-and-play nature, to reduce maintenance costs.Wind Energy/Aerospace Structures and Computational MechanicsAerospace Engineerin
Extension and Verification of Sequentially Linear Analysis to Solid Elements
No full textWhen analyzing three-dimensional problems with nonlinear finite element analysis (NLFEA) often problems are encountered such as bifurcation and divergence of the solution. In particular, cases subjected to tension softening tend to encourage the emergence of multiple equilibrium paths. In order to overcome these problems the Sequentially Linear Analysis (SLA) method has been developed for three-dimensional solid elements. SLA is an alternative for incremental-iterative solution schemes to model the nonlinear fracture behavior of quasi-brittle materials. It is an attractive method since it avoids the well known convergence and bifurcation problems that are often encountered when using incremental-iterative schemes such as Newton-Raphson. SLA uses a series of linear analyses to model the nonlinear behavior of the structure. By directly specifying a damage increment in each linear analysis, extensive iterations within the load or displacement increment can be avoided. The main objective of this research was to see how the Sequentially Linear Analysis approach could be extended to solid elements, so that it could be used for three-dimensional fracture problems as well. Although three-dimensional geometries such as masonry structures have been analyzed before using SLA, it was always restricted to two-dimensional finite elements only (shell elements). Therefore, first a theoretical constitutive model for three-dimensional stress-strain states has been developed that served as the starting point. Implementation in DIANA was the major second step from which the third and last step could be started: the verification on various fictive and real cases. A single element pull test was used to solve programming errors, whereas the notched beam offered the possibility to check how the newly developed SLA-code would perform for larger models. Both cases showed excellent agreement with the experiment. However, most attention was dedicated to the verification and physical interpretation of a real reinforced concrete slab. The results were critically evaluated, interpreted and compared to results from the experiment and the incremental-iterative Newton-Raphson method. It was concluded that the Sequentially Linear Analysis is able to properly capture the quasi-brittle behavior of the reinforced concrete slab. Especially in comparison to the three-dimensional Newton-Raphson results, SLA turned out to be more robust and accurate.Structural EngineeringCivil Engineering and Geoscience
Structural Optimization of Multi-Megawatt, Offshore Vertical Axis Wind Turbine Rotors: Identifying Structural Design Drivers and Scaling up of Vertical Axis Wind Turbine Rotors
No full textThe knowledge about Vertical Axis Wind Turbines (VAWT) lags behind the knowledge about Horizontal AxisWind Turbines (HAWT), since most of the development of VAWT’s ceased after the 80’s. A lack of insight exists about how certain design parameters affect the rotor design of a modern VAWT. The objective of this thesis is to gain knowledge about the influence of the size (power capacity) of the turbine on the structural rotor performance of multi-megawatt VAWT’s by optimizing the rotor design. The influence of the size is expressed by scaling trends. The scope is limited to the structural design of the rotor blade and struts. The major loads on the rotor structure are aerodynamic, gravitational, and centrifugal loads. Fatigue, buckling, and resonance are the failure modes driving the design of the VAWT rotor. Modern manufacturing techniques of composite materials are believed to have a significant effect on the VAWT rotor design, since they offer more flexibility in the blade geometry. The mass increase of the blades is identified as a limiting factor for upscaling wind turbines. Gradient-based optimizations are performed to find the optimum 3-bladed H-rotor and Darrieus rotor designs for different rotor sizes and heights. The structural rotor performance is assessed by the ratio of the rotor mass over projected area. The laminate thicknesses and the shape of the rotor structure are varied in search of the optimum performance. A constant tip speed ratio and blade solidity is imposed on the optimization. Furthermore, constraints are imposed to prevent failure of the rotor structure. Optimizations of the VAWT rotor are performed for rotor sizes ranging from 3 MW to 20 MW. Rotor mass reductions for the carbon-fiber 20 MW H-VAWT and Darrieus VAWT of respectively 35% and 44% are obtained with respect to the fiberglass HAWT rotors. Despite this mass reduction, the material cost of the HAWT rotor will be significantly smaller. The optimized VAWT rotors are rough approximations of the best design solutions because of restrictions on the design space. In general, expanding the design space of the optimization yields better design solutions. In future VAWT rotor design optimization, the design space should allow for a variable diameter-to-height ratio of the rotor, since this parameter is driving the structural rotor performance.Aerospace EngineeringWind Energ
Acceptance of Privacy-Sensitive Technologies: Smart Metering Case in The Netherlands
No full textOver recent years there have been several initiatives around the world that aim to roll out smart metering systems, especially within North America and member states of the European Union. Smart metering systems, giving essential conditions for smart grids in the energy sector, can offer services aimed at achieving many different goals beyond the main task of metering electricity consumption of households. Despite the many advantages gained by the smart metering system, there is a number of serious issues that may lead to the system’s failure or inability to reach its goals. One such obstacle which can lead to consumers’ rejection of smart meters is perceived security and privacy violations of consumers’ information. The social rejection of smart meters poses a significant threat to a successful rollout and operation of the system as consumers represent a cornerstone in the fulfillment of goals such as energy efficiency and savings, by their active interaction with the smart meters. To investigate consumers’ perception of smart meters theories and models from the technology acceptance literature can be used for understanding consumers’ behaviors, and exploring possible factors that can have a significant impact on consumers’ acceptance and usage of a smart meter. In this paper, a first-stage hybrid model of a two well-known technology acceptance theories is presented. These theories are: the Unified Theory of Acceptance and Usage of Technology- UTAUT, and Innovation Diffusion Theory- IDT. The hybrid model is further extended with additional acceptance determinants derived from the smart metering case in the Dutch context. The model aims to investigate determinants that can help shed the light on consumers’ perception of the system and its acceptance.Infrastructures, Systems and ServicesTechnology, Policy and Managemen
HiveArcs - Visualizing genome co-expression data
No full textThe developing human brain is a complex process, governed by the human genome. Understanding this development process is the key to understanding not only the connections between genes and brain functioning, but can also advance knowledge about disorders such as Alzheimer’s and Autism. The BrainSpan transcriptional atlas, released in 2013 by the Allen Institute for Brain Science, provides unique opportunities to study this process, but also challenges existing methods for visual analysis. One particular problem arises when large co-expression networks are subdivided in modules through clustering algorithms. In this work we introduce HiveArcs, an interactive online visual analysis for genome co-expression data. HiveArcs visualizes modules using arc diagrams on radially placed axes. Using this lay-out accommodates display of per-gene tracks of additional information as well as relationships between modules. This allows for quick and intuitive comparison between modules as well as in depth analysis of a single module.Medical VisualizationComputer GraphicsElectrical Engineering, Mathematics and Computer Scienc
ІНТЕГРАТИВНЕ УЗАГАЛЬНЕННЯ ФОРМ ІНТЕРАКТИВНИХ МЕТОДІВ НАВЧАННЯ
No full textThis article considers from and content interactively method theaching of repairing future teachers. The author of the analyses the condition effect interactively method studies
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