127 research outputs found

    Accurate Colour Reproduction of Human Face using 3D Printing Technology

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    The colour of the face is one of the most significant factors in appearance and perception of an individual. With the rapid development of colour 3D printing technology and 3D imaging acquisition techniques, it is possible to achieve skin colour reproduction with the application of colour management. However, due to the complicated skin structure with uneven and non-uniform surface, it is challenging to obtain accurate skin colour appearance and reproduce it faithfully using 3D colour printers. The aim of this study was to improve the colour reproduction accuracy of the human face using 3D printing technology. A workflow of 3D colour image reproduction was developed, including 3D colour image acquisition, 3D model manipulation, colour management, colour 3D printing, postprocessing and colour reproduction evaluation. Most importantly, the colour characterisation methods for the 3D imaging system and the colour 3D printer were comprehensively investigated for achieving higher accuracy

    Translational Functional Imaging in Surgery Enabled by Deep Learning

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    Many clinical applications currently rely on several imaging modalities such as Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), Computed Tomography (CT), etc. All such modalities provide valuable patient data to the clinical staff to aid clinical decision-making and patient care. Despite the undeniable success of such modalities, most of them are limited to preoperative scans and focus on morphology analysis, e.g. tumor segmentation, radiation treatment planning, anomaly detection, etc. Even though the assessment of different functional properties such as perfusion is crucial in many surgical procedures, it remains highly challenging via simple visual inspection. Functional imaging techniques such as Spectral Imaging (SI) link the unique optical properties of different tissue types with metabolism changes, blood flow, chemical composition, etc. As such, SI is capable of providing much richer information that can improve patient treatment and care. In particular, perfusion assessment with functional imaging has become more relevant due to its involvement in the treatment and development of several diseases such as cardiovascular diseases. Current clinical practice relies on Indocyanine Green (ICG) injection to assess perfusion. Unfortunately, this method can only be used once per surgery and has been shown to trigger deadly complications in some patients (e.g. anaphylactic shock). This thesis addressed common roadblocks in the path to translating optical functional imaging modalities to clinical practice. The main challenges that were tackled are related to a) the slow recording and processing speed that SI devices suffer from, b) the errors introduced in functional parameter estimations under changing illumination conditions, c) the lack of medical data, and d) the high tissue inter-patient heterogeneity that is commonly overlooked. This framework follows a natural path to translation that starts with hardware optimization. To overcome the limitation that the lack of labeled clinical data and current slow SI devices impose, a domain- and task-specific band selection component was introduced. The implementation of such component resulted in a reduction of the amount of data needed to monitor perfusion. Moreover, this method leverages large amounts of synthetic data, which paired with unlabeled in vivo data is capable of generating highly accurate simulations of a wide range of domains. This approach was validated in vivo in a head and neck rat model, and showed higher oxygenation contrast between normal and cancerous tissue, in comparison to a baseline using all available bands. The need for translation to open surgical procedures was met by the implementation of an automatic light source estimation component. This method extracts specular reflections from low exposure spectral images, and processes them to obtain an estimate of the light source spectrum that generated such reflections. The benefits of light source estimation were demonstrated in silico, in ex vivo pig liver, and in vivo human lips, where the oxygenation estimation error was reduced when utilizing the correct light source estimated with this method. These experiments also showed that the performance of the approach proposed in this thesis surpass the performance of other baseline approaches. Video-rate functional property estimation was achieved by two main components: a regression and an Out-of-Distribution (OoD) component. At the core of both components is a compact SI camera that is paired with state-of-the-art deep learning models to achieve real time functional estimations. The first of such components features a deep learning model based on a Convolutional Neural Network (CNN) architecture that was trained on highly accurate physics-based simulations of light-tissue interactions. By doing this, the challenge of lack of in vivo labeled data was overcome. This approach was validated in the task of perfusion monitoring in pig brain and in a clinical study involving human skin. It was shown that this approach is capable of monitoring subtle perfusion changes in human skin in an arm clamping experiment. Even more, this approach was capable of monitoring Spreading Depolarizations (SDs) (deoxygenation waves) in the surface of a pig brain. Even though this method is well suited for perfusion monitoring in domains that are well represented with the physics-based simulations on which it was trained, its performance cannot be guaranteed for outlier domains. To handle outlier domains, the task of ischemia monitoring was rephrased as an OoD detection task. This new functional estimation component comprises an ensemble of Invertible Neural Networks (INNs) that only requires perfused tissue data from individual patients to detect ischemic tissue as outliers. The first ever clinical study involving a video-rate capable SI camera in laparoscopic partial nephrectomy was designed to validate this approach. Such study revealed particularly high inter-patient tissue heterogeneity under the presence of pathologies (cancer). Moreover, it demonstrated that this personalized approach is now capable of monitoring ischemia at video-rate with SI during laparoscopic surgery. In conclusion, this thesis addressed challenges related to slow image recording and processing during surgery. It also proposed a method for light source estimation to facilitate translation to open surgical procedures. Moreover, the methodology proposed in this thesis was validated in a wide range of domains: in silico, rat head and neck, pig liver and brain, and human skin and kidney. In particular, the first clinical trial with spectral imaging in minimally invasive surgery demonstrated that video-rate ischemia monitoring is now possible with deep learning

    Verbesserung der Anwendbarkeit von organischen Leuchtdioden durch integrierte Nanostrukturen

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    The organic light-emitting diode (OLED) is a promising technology for a variety of applications, such as displays, large-area lighting, integrated sensing, smart packaging, and signage. OLEDs are thin-film devices comprising organic semiconductors, which allow for cost-efficient high-volume manufacturing using solution-based fabrications methods and therefore hold great potential towards disposable and recyclable electronic products. In this thesis, three different approaches to improve the applicability of OLEDs through integrated nanostructures are explored. Nanostructuring the carrier substrate's outside surface provides a way to enhance light extraction as well as customize tactile and visual device perception. Here, a polymer coating containing tetrapodal zinc oxide nanoparticles and color pigments is investigated with respect to surface roughness characteristics and optical properties. Electrical device properties can be altered by integrating nanostructures directly into the OLED semiconductor stack. In this work, periodic nanopatterning of a metal electrode is shown to improve charge injection into the organic semiconductor layer of a single-carrier device through local electric field enhancements. A current increase of up to 300 % is observed, exceeding the planar current injection limit and indicating a local transition to space charge limited operation. Integration of a photonic crystal slab into the waveguide formed by the OLED can also lead to resonant light outcoupling. Here, a fabrication method is presented to create two-dimensional nanogratings with variable grating designs in the commonly used electrode material indium tin oxide. Furthermore, a novel device structure is investigated in which a fluorescent nanopatterned waveguide is placed outside the OLED for directional light emission leading to sharp angle-dependent outcoupling peaks in the emission spectra

    Aiding the conservation of two wooden Buddhist sculptures with 3D imaging and spectroscopic techniques

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    The conservation of Buddhist sculptures that were transferred to Europe at some point during their lifetime raises numerous questions: while these objects historically served a religious, devotional purpose, many of them currently belong to museums or private collections, where they are detached from their original context and often adapted to western taste. A scientific study was carried out to address questions from Museo d'Arte Orientale of Turin curators in terms of whether these artifacts might be forgeries or replicas, and how they may have transformed over time. Several analytical techniques were used for materials identification and to study the production technique, ultimately aiming to discriminate the original materials from those added within later interventions

    Trademarks and Textual Data: A Broader Perspective on Innovation = Marques et données textuelles : Une perspective élargie sur l’innovation

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    Patente messen häufig technische Innovationen, während Handelsmarken Low-Tech und Dienstleistungen abdecken. In dieser Arbeit werden Textdaten von Marken untersucht, um verschiedene Rechte des geistigen Eigentums zu kombinieren. Textdaten ermöglichen zum Beispiel die Analyse großer Datenmengen, die Kombination verschiedener Quellen und datengestützte Erkenntnisse. Die Kombination von Handelsmarken und Patenten in den Bereichen Robotik (Hightech) und Schuhe (Lowtech) bietet eine breitere Abdeckung und Details zu Innovationen, die je nach Sektor variieren. Im Musikinstrumentensektor verdeutlichen Textdaten zu Marken, Patenten und Designs den laufenden technologischen Wandel. Patente beziehen sich auf Daten und Digitalisierungsthemen und werden von High-Tech-Firmen genutzt, während Handelsmarken die Signalverarbeitung und Videospiele von Spielfirmen abdecken. Designs fungieren als verbindendes Element. Eine Differenzierung zwischen Unternehmen und Tätigkeitsbereichen ist möglich. Zusammenfassend zeigt die These, dass die Integration von textuellen Markendaten die Innovationsabdeckung erweitert

    Experimental investigation of an indoor air purification system using an innovative photocatalytic mop

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    This thesis presents a comprehensive investigation of "MopFan," a photocatalytic air purification system, with the overarching goal of improving indoor air quality and its broader impacts on public health, the environment, and the economy. Recognising the critical importance of addressing the pressing issue of air pollution, this study delves into various facets of the MopFan technology and its potential for revolutionising the field of air purification. To lay the foundation for this research, a thorough review of the existing literature on photocatalytic purifiers is conducted, providing a comprehensive understanding of the current state-of-the-art in air purification technology. By analysing the strengths and limitations of previous studies, this review identifies crucial areas for improvement, particularly in the domains of filter design, catalyst selection, and lighting arrangement. By pinpointing these areas, the study aims to contribute to the ongoing efforts to enhance the efficacy and efficiency of air purification systems. Building upon this literature review, the research explores novel approaches to fibre configuration and coating for anti-virus protection within the MopFan system. Through experimentation and analysis, the study uncovers the significant effectiveness of copper, tampico, and coco fibres in mitigating viral contaminants, offering a promising solution to combat airborne pathogens. This discovery holds immense potential for shaping future strategies in filter design and material selection, opening new possibilities for the development of advanced air purification technologies. The thesis then proceeds to focus on the practical implementation of the MopFan technology by designing, prototyping, and rigorously testing prototypes. Each prototype represents a significant advancement in air purification capabilities, showcasing the integration of motor-driven fans, specialised mop technology, and enhanced UV light to maximise the removal of airborne pollutants. Through a comprehensive evaluation of these prototypes, the research demonstrates efficacy in significantly improving air quality and reducing the presence of harmful particles in indoor environments. This research utilised 3D printing technology to create functional prototypes of the MopFan air purification system, focusing on advancements in air purification capabilities. The prototypes were produced using a specialised 3D printer and ABS filament, with the hub divided into sections for individual printing and easy assembly. Precision was achieved through careful adjustment of printer settings, resulting in accurate prototypes. Although the printing process took 12 to 16 hours per prototype, it enabled efficient construction, comprehensive evaluation, and testing. In addition to the technical aspects, this thesis also delves into the economic and environmental dimensions of the MopFan technology. An economic assessment showcases the potential for job creation and economic growth associated with the widespread adoption and commercialisation of the technology. By highlighting the economic benefits, this assessment serves as a compelling argument for the financial feasibility and further development. Simultaneously, an environmental assessment emphasises the importance of adopting sustainable practices throughout the lifecycle of the technology. It emphasises the need for responsible manufacturing, energy efficiency, and waste reduction, highlighting the imperative of creating environmentally conscious solutions to address air pollution

    6th International Meeting on Retouching of Cultural Heritage, RECH6

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    RECH Biennial Meeting is one of the largest educational and scientific events in Retouching field, an ideal venue for conservators and scientists to present their research results about retouching. The main focus will be to promote the exchange of ideas, concepts, terminology, methods, techniques and materials applied during the retouching process in different areas of conservation: mural painting, easel painting, sculpture, graphic documentation, architecture, plasterwork, photography, contemporary art, among others. This Meeting aims to address retouching by encouraging papers that contribute to a deeper understanding of this final task of the conservation and restoration intervention. The main theme embraces the concepts of retouching, the criteria and limits in the retouching process, the bad retouching impact on heritage and their technical and scientific developments.This Meeting will discuss real-life approaches on retouching, focusing on practical solutions and on sharing experiencesColomina Subiela, A.; Doménech García, B.; Bailão, A. (2023). 6th International Meeting on Retouching of Cultural Heritage, RECH6. Editorial Universitat Politècnica de València. https://doi.org/10.4995/RECH6.2021.1601
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