14 research outputs found
Flexibly formed concrete: Exploiting the deformation behaviour of weft-knitted formworks caused by concrete pressure
No full textTo reduce the construction industry’s negative influence on global climate, emissions related to concrete consumption need to be addressed. This implies reducing the amount concrete used, by creating material-efficient structures. One of concrete’s main advantages is that it can be moulded into virtually any shape. Despite the fact that modern digital design tools enable the effortless design and calculation of lightweight and graceful structures, this potential often goes unrealised. This can be attributed to the challenges associated with constructing intricate and custom geometries using conventional formwork techniques that depend on single-use cut timber or milled foam. Not only do these methods make the construction of these types of structures labour and cost intensive, they also cause them to be wasteful.KnitCrete, which uses knitted technical textiles as stay-in-place moulds for concrete structures, has proven to be a solution for building doubly curved structures, eliminating the need for time-consuming, costly, and wasteful moulds. However, due to its inherent high flexibility and the challenges of predicting and controlling the geometry during the casting process, the technology relies on coating procedures using high-strength cement paste coating to stiffen the geometry before concrete can be poured.This research addresses both issues and proposes a design approach, which models the deformation behaviour of the uncoated knitted formwork under concrete pressure to determine the final geometry of flexibly formed concrete structures, hence gaining better understanding on the deformation behaviour of knitted textile formworks and bypassing the stiffening steps during fabrication.Developing a method to predict the final geometry of flexibly formed concrete structures involves various research disciplines, including material science, and structural mechanics. The research approach is divided into three parts. The first part investigates the stress-strain relationship of various textiles with different knitting patterns, alongside the rheological and mechanical strength properties of different cementitious mixtures. The second stage focuses on developing (semi-)analytical models to predict the deflection behaviour of membranes subjected to varying boundaries, loads, and material properties. Finally, the accuracy of the models are validated by the construction of multiple prototypes.In conclusion, this thesis introduces a fabrication system that exploits the deflection behaviour of flexible formworks to create funicular shell structures and lays the foundation for implementing (semi-)analytical approaches to model these deformations.Civil Engineerin
A Quantitative Comparison of the Material-Use for a Form Found and a Conventional Concrete Pedestrian Bridge
No full textConcrete is the most used building material in the world. Its success can be linked back to its mouldability, durability and low cost. Unfortunately, current conventional concrete pedestrian bridge designs do not benefit from these key features and still require bulky shaped cross-sections, whereby part of the concrete does not contribute to the structural strength. This study assesses the potential reduction of material use by combining shot-crete 3D printing (SC3DP) with the application of textile formworks for the production of form found pedestrian bridges, instead of the conventional design and fabrication process.The present thesis looks at conventional concrete pedestrian bridge design and form found concrete for it examined for four different spans: 5 m, 10 m, 20 m and 45 m. The designs are tested for full vertical loading, asymmetric vertical loading, and buckling. The amount of material required for each span and load case are determined and compared with each other. The results show that the form found concrete pedestrian bridge designs only re-quire a fraction (between 13.0% and 20.0%) of the amount of concrete used for the same design with conventional approaches. The form found concrete pedestrian bridge designs become more material efficient than the conventional designs as the span increases. Dur-ing the calculation process it was ascertained that the conventional concrete pedestrian bridge design cannot reach spans larger than 20 m. It was also observed that the concrete thickness of the shorter span form found concrete pedestrian bridges (5 m and 10 m) is governed by the asymmetric load case and the concrete thickness of the longer span form found concrete pedestrian bridges (20 m and 45 m) is governed by the buckling case. Over-all it can be concluded that the form found concrete pedestrian bridge design is superior with regards to the material use, when compared to the conventional concrete pedestrian bridge design.Additional thesisCivil Engineerin
Energy-Efficient SNN Implementation Using RRAM-Based Computation In-Memory (CIM)
No full textSpiking Neural Networks (SNNs) can drastically improve the energy efficiency of neuromorphic computing through network sparsity and event-driven execution. Thus, SNNs have the potential to support practical cognitive tasks on resource constrained platforms, such as edge devices. To realize this, SNN requires energy-efficient hardware which can run applications with a limited energy budget. However, the conventional CMOS implementations cannot achieve this goal due to the various architectural and technological challenges. In this work, we address these issues by developing an energy-efficient and accurate SNN hardware based on Computation In-Memory (CIM) architecture using Resistive Random Access Memory (RRAM) devices. The developed SNN architecture is based on unsupervised Spike Time Dependent Plasticity (STDP) learning algorithm with online learning capability. Simulation results show that the proposed architecture is energy-efficient with a consumption of ≈20 fJ per spike, while maintaining state-of-the-art inference accuracy of 95% when evaluated using the MNIST dataset.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.Computer EngineeringQuantum & Computer Engineerin
Navigating the Energy Transition: A Comprehensive Modeling Approach for the Netherlands
No full textThis report presents an energy transition model that emphasizes the importance of prioritizing innovation. It demonstrates the potential energy savings achievable through the installation of insulation layers. Additionally, it explores the increasing adoption of electric vehicles (EVs) and its influence on energy consumption within the transportation sector. The report also discusses renewable energy sources and explores energy storage methods. Lastly, the report concludes by highlighting the need for a balance between energy supply and demand, acknowledging that traditional energy sources will continue to be necessary in 2030, aligning with expectations. This comprehensive analysis serves as a foundation for future research endeavors aimed at developing a more precise model.EE3L11Electrical Engineerin
Semi-fragile watermarking for digital-capture image on handheld device within a certification chain
No full textLes smartphones équipent désormais toutes les couches de la population, indépendamment de l'âge ou de la profession. Ces équipements sont de plus en plus utilisés pour créer, manipuler et diffuser des informations contraintes par la sécurité (confidentialité, intégrité, authenticité). Plusieurs moyens de protection existent selon le type d'informations et les contraintes de sécurité (droit d'auteur, traçabilité, etc.). Cette thèse propose une solution de tatouage spécifique à l'image capturée depuis un smartphone afin de la rendre valable en justice. Son objectif est de lier la preuve à l'image et d'empêcher toute modification du contenu de l'image ainsi que des éléments de preuve. La confidentialité de l?image n'étant pas recherchée, le tatouage présente l'intérêt de conserver la lisibilité de l'image probante et donc autorise sa diffusion. La preuve est aussi constituée des données contextuelles de l'image: son auteur, la date de prise de vue ou encore sa position géographique. Peu de moyens sont disponibles pour vérifier cette géolocalisation. La seconde partie de la thèse propose ainsi des méthodes logicielles permettant la mise en oeuvre de contrôles destinés à améliorer l'authenticité de la géolocalisation. Enfin, le dernier chapitre propose une analyse critique des travaux de sécurité concernant les autres besoins d'authentification nécessaire à la réalisation d'une bonne preuveSmartphones are nowadays ubiquitous, they can be found in anybody's hands with no consideration of one's age or work. They are used to create, manipulate and broadcast security constrained pieces of information (in term of confidentiality, integrity or authenticity). Different protection types can be found, with regard to the security constraints (copyrights, document tracking, etc.). This thesis presents a watermarking scheme tailored for smartphone-captured images, which scheme allows the use of the image as an evidence. The goal is linking the evidence to the image and forbidding any content modification. Confidentiality not being a constraint, the scheme keeps the image visible and allow its broadcast. Contextual pieces of data are part of the evidence: author name, date of shot and geographic location (geolocation). Few means are available to assess this geolocation. The second part of the thesis aims to fill this gap by proposing software based countermeasures to enhanced geolocation authenticity. Finally, the last chapter presents a critic of security works on the other authentication methods required to forge a strong proo
Electrostatic Dust Removal System for a Lunar Rover Solar Panel Assembly: Electronics Design
No full textLunar dust presents a serious problem for future lunar rovers. Due to the charged nature of this fine dust, it tends to stick to sensitive elements like solar panels. It is clear that a system needs to be implemented in order to remove lunar dust to keep the output power of the solar panel at a satisfactory level. This paper develops the proof of concept electronics for a method sometimes called an electrodynamic screen, that uses electrostatic fields to sweep away the dust adhered to the surface of the solar panel. The electronics for this system needs to produce a high voltage three phase pulse wave in order to drive the electrodes placed on top of the solar panel. The design of the electrodes themselves are not part of this thesis, but it is the main subject of the companion thesis produced by other members of our group.Electrical Engineerin
EdgeShield: a robust and agile cybersecurity architecture for the internet of medical things
Full text linkWe present EdgeShield, a lightweight pipeline that streamlines internet of medical things (IoMT) traffic analysis by pairing aggressive dimensionality-reduction with federated model aggregation. It employs systematic preprocessing, advanced feature selection, and robust sampling to reduce computational overhead while enhancing performance. Through feature engineering techniques such as principal component analysis (PCA), targeted feature selection, and embedding methods, EdgeShield reduces dataset dimensionality by 96%, enabling near real-time detection and prevention of cyber attacks on resource-constrained edge devices. To harden the IoMT perimeter, EdgeShield trains ten lightweight edge models in just 54s and merges their parameters into a single global clas sifier with negligible extra delay. This method requires no additional training or predictions, thus accelerating deployment. Additionally, by using a compact dataset with five top-performing features and PCA with two components, EdgeShield consistently achieves accuracy levels exceeding 99.2% for individual edge models and the consolidated global model. With a built-in continuous improvement loop, EdgeShield dynamically adapts to emerging data patterns and operational conditions, driving substantial advancements in IoMT ecosystem management. This approach delivers both rapid machine learning model deployment and robust cyber attack detection, illustrating its potential to revolutionize IoMT security and elevate healthcare data integrity
A cárie dentária do ponto de vista microbiológico: revisão narrativa
No full textO objetivo desta tese é realizar uma revisão bibliográfica narrativa sobre a cárie dentária do ponto de vista microbiológico. Em particular, descreve a constituição do biofilme dental saudável e patológico e suas diferentes fases de desenvolvimento. Também o seu envolvimento no desenvolvimento da cárie dentária através dos diversos microrganismos quem o coloniza. Além disso, uma transmissão dessas bactérias entre mãe e filho foi demonstrada por estudos citados. Existem fatores de riscos que aumentam a sua probabilidade de ocorrência. Mas existem meios eficazes de prevenção contra o seu desenvolvimento.
Trabalho consistiu na realização de uma pesquisa bibliográfica em diferentes bases de dados eletrónicas, nomeadamente: B-on, Pubmed, Researchgate e Science direct com o intuito de “cárie dentária”, “biofilme dentário”, “S.mutans”, “bacterias”, “Lactobacillus”, “Actinomyces”.
Foram incluídos artigos completos sobre o assunto, revisões e estudos com seres humanos em inglês, português e francês. Os artigos relevantes para a revisão foram escolhidos pelo autor de acordo com aqueles que obedeciam aos critérios de inclusão estabelecidos.
Concluiu-se que a cárie dentária é uma doença causada por um desequilíbrio de microrganismos na flora oral. Existem alguns fatores que aumentam o risco de cárie dentária. O tratamento da cárie dentária depende da sua extensão.The objective of this dissertation is to carry out a narrative bibliographic review on dental caries from a microbiological point of view. In particular, describe the different phases of the dental biofilm and its development. Also its involvement in the development of dental caries through the various microorganisms that colonize it. Furthermore, the transmission of bacteria between mother and child has been demonstrated by studies. There are risk factors that increase its probability of occurrence. However, there are effective means of preventing its development.
The work consisted in carrying out a bibliographic search in different electronic databases, namely: B-on, Pubmed, Researchgate and Science direct with the aim of “dental caries”, “dental biofilm”, “S.mutans”, “bacteria”, “Lactobacillus”, “Actinomyces”.
Full articles on the subject, reviews and studies with human beings in English, Portuguese and French were included. The author according to those that met the established inclusion criteria chose articles relevant to the review.
In conclusion, that dental caries is a disease caused by an imbalance of microorganisms in the oral flora. There are some factors that increase the risk of tooth decay. The treatment of tooth decay depends on his extension
Tatouage d'image semi-fragile pour appareil mobile intégré dans une chaîne de certification
No full textSmartphones are nowadays ubiquitous, they can be found in anybody's hands with no consideration of one's age or work. They are used to create, manipulate and broadcast security constrained pieces of information (in term of confidentiality, integrity or authenticity). Different protection types can be found, with regard to the security constraints (copyrights, document tracking, etc.). This thesis presents a watermarking scheme tailored for smartphone-captured images, which scheme allows the use of the image as an evidence. The goal is linking the evidence to the image and forbidding any content modification. Confidentiality not being a constraint, the scheme keeps the image visible and allow its broadcast. Contextual pieces of data are part of the evidence: author name, date of shot and geographic location (geolocation). Few means are available to assess this geolocation. The second part of the thesis aims to fill this gap by proposing software based countermeasures to enhanced geolocation authenticity. Finally, the last chapter presents a critic of security works on the other authentication methods required to forge a strong proofLes smartphones équipent désormais toutes les couches de la population, indépendamment de l'âge ou de la profession. Ces équipements sont de plus en plus utilisés pour créer, manipuler et diffuser des informations contraintes par la sécurité (confidentialité, intégrité, authenticité). Plusieurs moyens de protection existent selon le type d'informations et les contraintes de sécurité (droit d'auteur, traçabilité, etc.). Cette thèse propose une solution de tatouage spécifique à l'image capturée depuis un smartphone afin de la rendre valable en justice. Son objectif est de lier la preuve à l'image et d'empêcher toute modification du contenu de l'image ainsi que des éléments de preuve. La confidentialité de l?image n'étant pas recherchée, le tatouage présente l'intérêt de conserver la lisibilité de l'image probante et donc autorise sa diffusion. La preuve est aussi constituée des données contextuelles de l'image: son auteur, la date de prise de vue ou encore sa position géographique. Peu de moyens sont disponibles pour vérifier cette géolocalisation. La seconde partie de la thèse propose ainsi des méthodes logicielles permettant la mise en oeuvre de contrôles destinés à améliorer l'authenticité de la géolocalisation. Enfin, le dernier chapitre propose une analyse critique des travaux de sécurité concernant les autres besoins d'authentification nécessaire à la réalisation d'une bonne preuv
Tatouage d'image semi-fragile pour appareil mobile intégré dans une chaîne de certification
No full textSmartphones are nowadays ubiquitous, they can be found in anybody's hands with no consideration of one's age or work. They are used to create, manipulate and broadcast security constrained pieces of information (in term of confidentiality, integrity or authenticity). Different protection types can be found, with regard to the security constraints (copyrights, document tracking, etc.). This thesis presents a watermarking scheme tailored for smartphone-captured images, which scheme allows the use of the image as an evidence. The goal is linking the evidence to the image and forbidding any content modification. Confidentiality not being a constraint, the scheme keeps the image visible and allow its broadcast. Contextual pieces of data are part of the evidence: author name, date of shot and geographic location (geolocation). Few means are available to assess this geolocation. The second part of the thesis aims to fill this gap by proposing software based countermeasures to enhanced geolocation authenticity. Finally, the last chapter presents a critic of security works on the other authentication methods required to forge a strong proofLes smartphones équipent désormais toutes les couches de la population, indépendamment de l'âge ou de la profession. Ces équipements sont de plus en plus utilisés pour créer, manipuler et diffuser des informations contraintes par la sécurité (confidentialité, intégrité, authenticité). Plusieurs moyens de protection existent selon le type d'informations et les contraintes de sécurité (droit d'auteur, traçabilité, etc.). Cette thèse propose une solution de tatouage spécifique à l'image capturée depuis un smartphone afin de la rendre valable en justice. Son objectif est de lier la preuve à l'image et d'empêcher toute modification du contenu de l'image ainsi que des éléments de preuve. La confidentialité de l?image n'étant pas recherchée, le tatouage présente l'intérêt de conserver la lisibilité de l'image probante et donc autorise sa diffusion. La preuve est aussi constituée des données contextuelles de l'image: son auteur, la date de prise de vue ou encore sa position géographique. Peu de moyens sont disponibles pour vérifier cette géolocalisation. La seconde partie de la thèse propose ainsi des méthodes logicielles permettant la mise en oeuvre de contrôles destinés à améliorer l'authenticité de la géolocalisation. Enfin, le dernier chapitre propose une analyse critique des travaux de sécurité concernant les autres besoins d'authentification nécessaire à la réalisation d'une bonne preuv
