Een experimenteel glasvezelsysteem voor videotransmissie met behulp van puls-frequentiemodulatie

Een experimenteel glasvezelsysteem werd ontworpen en gerealiseerd voor videotransmissie waarbij met name de ontvanger optimaal is aangepast aan het ruisgedrag van pulsfrequentiemodulatie. De ontvangversterker als een actief filter gedimensioneerd, zodat de parasitaire capaciteiten nuttig gebruikt konden worden. Het verslag begint met enkele opmerkingen over eigenschappen en beperkingen van verschillende onderdelen van een glasvezelverbinding. Daarna worden verschillende mogelijke modulatiemethoden met elkaar vergeleken. Met behulp van een computerprogramma is gezocht naar een optimale ontvangfilterkarakteristiek in verband met ruis en vervorming. Aan de hand van de resultaten wordt een geschikte filterkarakteristiek uitgekozen, die in het gerealiseerde systeem toegepast wordt. De invloed van veroudering van de ingangstransistor bij de ontvangversterker op de signaal-ruisverhouding na demodulatie is ook berekend. Het gerealiseerde systeem wordt beschreven en enkele uitkomsten van metingen aan dit systeem worden daarna vergeleken met de computerberekeningen.Electrical Engineering, Mathematics and Computer ScienceTransmissie van Informati

Flexible mould for production of double-curved concrete elements

This thesis focuses on the consequences of deforming a flexible mould surface. Based on the findings a new mould design was developed in order research the deformation of the mould. Also a method was developed to obtain an accurate geometry of the mould surface.Structural DesignStructural EngineeringCivil Engineering and Geoscience

Scanning in 3D and analysing the models of Heinz Isler, the preliminary results

During his live Heinz Isler built around 1400 shell structures, until he deceased in 2009. Heinz Isler is part of a Swizz tradition of structural art in the 20th century, which includes engineers such as Robert Maillart, Othmar Ammann und Christian Menn [1]. During his live Heinz Isler developed several methods for physical form finding of his shell structures [2, 3]. Methods such as hanging models, inflated membranes etc. The physical scale model where used for determining the strains and stresses in the shell structure. This was done by loading the scale models and measuring the strains and consequently calculating the stresses. The geometry of the scale models was used for the actually build shell structures by precisely measuring the scale models and scaling these up to the real size shell. Analysing Isler’s shells has always been impossible because Isler never published the precise geometry of his shell structures. Isler’s model where scanned for the first time ever in 2011, the results where used to construct NURBS (Non Uniform Rational B-spline) surfaces which describe the exact geometry of Isler’s scale models. The results are used for all kinds of analysis, such as finite element (FEM) calculations, curvature analysis etc. This means that for the first time a qualitative investigation can be made of Isler’s shell structures. This paper will present the first results. Hopefully it will give us a greater insight in the relation between geometry and the structural behaviour of shell structures.Architectural Engineering +TechnologyArchitecture and The Built Environmen

Reverse engineering of free form shell structures: From point cloud to finite element model

Many free form shell structures that have been designed and build in previous decades are fascinating structures. We can learn from these structures by analysing them and studying their structural behaviour. However, in some cases the geometry of these structures is not available; most notably the shapes of shell structures designed and build by Heinz Isler, who has built over 1400 shells. The geometry of many of his scale models and build structures have been obtained by the authors by making use of 3D laser scanners which create point clouds.This paper presents a method for reverse engineering of free form shell structures from point cloud to finite element model. Since shape and force interact, special attention is given to the geometric accuracy. Every model must be sufficiently accurate. The method has been applied to data obtained by scanning Isler’s shells. Important aspects that influence the quality of the resulting finite element model are described.Structural Design & Mechanic

Concepts and prototypes for flexible moulds for production of double curved elements

Flexible moulds for production of double curved elements could offer a solution for challenges in realizing freeform architectural design which tends to be costly and time consuming. However developments are still ongoing and promising methods that result in highly accurate elements still remain to be proven. When surfaces are deformed into a specific shape inaccuracies occur easily due to bucking or wrinkling of the surfaces. In this paper a number of concepts are presented which can be used to prevent these effects. The concepts are based on a fundamental relationship between change of Gaussian curvature of surfaces and in-plain strain. Various prototypes that have been made using these concepts will be presented.Architectural Engineering +TechnologyArchitecture and The Built Environmen

Maakbaarheid: Flexibele herbruikbare mal

Structural EngineeringCivil Engineering and Geoscience

Mapping double-curved surfaces for production of precast concrete shell elements

Practical implications of deforming a flat mould surface into a double-curved shape. Proposal for processing concrete elements with a complex double-curved geometry in an efficient and accurate manner using parametric, associative modelling.Steel & Composite StructuresStructural Design & Mechanic

Re-flex: Responsive Flexible Mold for Computer Aided Intuitive Design and Materialization

The paper presents an ongoing research about the design and a possible use of a responsive flexible mold. The mold is developed by integrating its precedents with automation and Human-Computer Interaction (HCI). The objective of the design is to provide an immersive design tool which has direct link to fabrication. It allows intuitive interaction to its user in order to help with the design and production of complex forms by supporting the designer's implicit skills with computer. The paper presents the design by illustrating the use of the hardware such as the actuators, the sensor and the projector; and by defining the workflow within the software. The paper concludes with the description of a possible use case in which the system is used to design and materialize an object in different scales.Design InformaticsStructural Design & Mechanic

Transparent form-active system with structural glass

Free-form transparent wide-span spatial structures which have being constructed so far, are based on the concept of three sets of components, the structural components, usually steel elements to ensure both compressive and tensional capacity; the glass cladding elements for expressing transparency; and thirdly an in between set for connecting the cladding with the primary skeleton. Even though glass technology is becoming more and more promising, glass is still considered doubtful in a load-bearing capacity, which implies to a repetitive architectural and engineering repertoire. Nevertheless, in the last two decades there has been a tendency to explore the design and realization of pure structural glass domes [1, 2, 3,4]. The outcome of these experiments, resulted in glass domes of the same conservative geometry of a sphere of small spans between 5-12.5m. Therefore, the glass still has not reached its limits in terms of architectural forms and span size. Apparently, the combination of synclastic and anticlastic geometries applied for glass structures is still an unknown field and remains as a theoretical question whether or not there are possibilities to implement glass plates in the construction of free-form spatial structures, as a main load-bearing component. In respect to the emerging technologies of glass technology and computation, design strategies revolving around the assumption of using glass to realize a transparent form-active system, are presented through a new concept for an innovative connection method. In particular, the concept of connection relies on the composition of a transparent hybrid composite composed by thermally strengthened glass, sentry glass plus and woven fabric composite. Particularly, the composite has an extended part outwards of a reinforced glass plate, used for easy assembly and disassembly as well as the transfer of tensile forces and improving so the post breakage behavior. The complete system out of glass plates and joints is controlled by determining the appropriate stiffness during design. The ultimate target, is to apply the concept of this joining method to any free-form shell geometry constructed out of planar glass plates.Architectural Engineering +TechnologyArchitecture and The Built Environmen

Optimization of complex-geometry high-rise buildings based on wind load analysis

As technology advances, architects often employ innovative, non-standard shapes in their designs for the fast-growing number of high-rise buildings. Conversely, climate change is bringing about an increasing number of dangerous wind events causing damage to buildings and their surroundings. These factors further complicate the already difficult field of structural wind analysis. Current methods for calculating structural wind response, such as the Eurocode, do not provide methods for unconventional building shapes or, in the case of physical wind tunnel test and in-depth computational fluid dynamics (CFD) simulation, they are prohibitively expensive and time-consuming. Thus, wind load analysis is often relegated to late in the design process. This paper presents the development of a computational method to analyze the effect of wind on the structural behavior of a 3D building model and optimize the external geometry to reduce those effects at an early design phase. It combines CFD, finite-element analysis (FEA), and an optimization algorithm in the popular parametric design tool, Grasshopper. This allows it to be used in an early design stage for performance-based design exploration in complement to the more traditional late-stage methods outlined above. After developing the method and testing the timeliness and precision of the CFD, and FEA portions on case study buildings, the tool was able to output an optimal geometry as well as a database of improved geometric options with their corresponding performance for the wind loading.Design InformaticsStructural Design & Mechanic