- About
-
The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
provided by the
Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
Search results
Showing 1 to 10 of 11 (0.065 seconds)| 1 |
High power conical-shaped Niobium targets for reliable [18F-] production and lower [18O] water consumptionDevillet, F., Geets, J.-M., Ghyoot, M., Kral, E., Mooij, R., Nactergal, B., Vosjan, M. 19 May 2015 (has links) (PDF)
Introduction
In order to address the increasing demand for Fluorine-18 and the rising cost per mL of 18O enriched water, IBA developed improvements to their 18F- production systems. For this new design we started from scratch, with the main objectives of reducing the required enriched water volume and improving the cooling of the insert. A better cooling allows increasing the target current and thus the produced activity. Finally, we aimed to reduce the number of parts and improve the design of auxiliary components.
Material and Methods
Six Niobium conical inserts with different target chamber volumes were machined and tested. Only 4 of these were selected to create the new range of IBA 18F− targets shown in TABLE 1. The new Niobium target inserts have a complex shape with drilled channels on the outside of the chamber and a deep channel next to the beam strike area (FIG. 1, green circle) to ensure efficient cooling.
The 18O water inlet lines are now directly inserted in the Niobium body (FIG. 1, blue circle) to improve 18F- quality (no more contact with small o-rings). In operation, a 35µm Havar® target window is used.
All tests were performed using IBA Cyclone® 18 cyclotron. The targets were filled with different volumes of enriched 18O water (enrichment
> 92 %) and irradiated with 18 MeV protons on target with beam currents up to 145 μA for 30 to 150 minutes, while the internal pressure rise of the target was recorded. For each target, a pressure-current curve was plotted and an optimum balance between target water fill volume, pressure and current has been determined, which maximises available activity after two hours, in each case.
Results and Conclusion
Radionuclidic impurities were measured and more than 100 FDG syntheses on various synthesizers confirmed the effectiveness of the new design. Increasing the current up to 145µA in Conical 16, the production reached 18 Ci in 2 hours, single beam, with a target pressure under 43 bar. Today, the use of these new targets for daily commercial production is increasing within the IBA Cyclone® installed base.
|
| 2 |
High power conical-shaped Niobium targets for reliable [18F-] production and lower [18O] water consumption: High power conical-shaped Niobium targets for reliable [18F-] production and lower [18O] water consumptionDevillet, F., Geets, J.-M., Ghyoot, M., Kral, E., Mooij, R., Nactergal, B., Vosjan, M. January 2015 (has links)
Introduction
In order to address the increasing demand for Fluorine-18 and the rising cost per mL of 18O enriched water, IBA developed improvements to their 18F- production systems. For this new design we started from scratch, with the main objectives of reducing the required enriched water volume and improving the cooling of the insert. A better cooling allows increasing the target current and thus the produced activity. Finally, we aimed to reduce the number of parts and improve the design of auxiliary components.
Material and Methods
Six Niobium conical inserts with different target chamber volumes were machined and tested. Only 4 of these were selected to create the new range of IBA 18F− targets shown in TABLE 1. The new Niobium target inserts have a complex shape with drilled channels on the outside of the chamber and a deep channel next to the beam strike area (FIG. 1, green circle) to ensure efficient cooling.
The 18O water inlet lines are now directly inserted in the Niobium body (FIG. 1, blue circle) to improve 18F- quality (no more contact with small o-rings). In operation, a 35µm Havar® target window is used.
All tests were performed using IBA Cyclone® 18 cyclotron. The targets were filled with different volumes of enriched 18O water (enrichment
> 92 %) and irradiated with 18 MeV protons on target with beam currents up to 145 μA for 30 to 150 minutes, while the internal pressure rise of the target was recorded. For each target, a pressure-current curve was plotted and an optimum balance between target water fill volume, pressure and current has been determined, which maximises available activity after two hours, in each case.
Results and Conclusion
Radionuclidic impurities were measured and more than 100 FDG syntheses on various synthesizers confirmed the effectiveness of the new design. Increasing the current up to 145µA in Conical 16, the production reached 18 Ci in 2 hours, single beam, with a target pressure under 43 bar. Today, the use of these new targets for daily commercial production is increasing within the IBA Cyclone® installed base.
|
| 3 |
Two-dimensional conjugated metal–organic frameworks (2D c-MOFs): chemistry and function for MOFtronicsWang, Mingchao, Dong, Renhao, Feng, Xinliang 17 May 2024 (has links)
The 21st century has seen a reinvention of how modern electronics impact our daily lives; silicon-electronics and organic electronics are currently at the core of modern electronics. Recent advances have demonstrated that conductive metal–organic frameworks (MOFs), as another unique class of electronic materials, are emerging to provide additional possibility for multifunctional electronic devices that brings us “MOFtronics”. Typically, two-dimensional conjugated MOFs (2D c-MOFs) are a novel class of layer-stacked MOFs with in-plane extended π-conjugation that exhibit unique properties such as intrinsic porosity, crystallinity, stability, and electrical conductivity as well as tailorable band gaps. Benefiting from their unique features and high conductivity, 2D c-MOFs have displayed great potential for multiple high-performance (opto)electronic, magnetic, and energy devices. In this review article, we introduce the chemical and synthetic methodologies of 2D c-MOFs, intrinsic influences on their electronic structures and charge transport properties, as well as multifunctional applications of this class of materials for MOFtronics and potential power sources for MOFtronics. We highlight the benefits and limitations of thus-far developed 2D c-MOFs from synthesis to function and offer our perspectives in regard to the challenges to be addressed.
|
| 4 |
Correction: Two-dimensional conjugated metal–organic frameworks (2D c-MOFs): chemistry and function for MOFtronicsWang, Mingchao, Dong, Renhao, Feng, Xinliang 17 May 2024 (has links)
Correction for ‘Two-dimensional conjugated metal–organic frameworks (2D c-MOFs): chemistry and function for MOFtronics’ by Mingchao Wang et al., Chem. Soc. Rev., 2021, 50, 2764–2793, DOI: 10.1039/D0CS01160F.
|
| 5 |
Processing of waste carbon and polyamide fibers for high performance thermoplastic composites: A novel manufacturing technology for unidirectional tapes structureKhushid, Muhammad Furqan, Hasan, Mir Mohammad B, Abdkader, Anwar, Cherif, Chokri 27 March 2023 (has links)
This paper presents an innovative, eco-friendly and sustainable tape manufacturing technology that transforms waste carbon and polyamide fibers into a new class of fibrous structure with unidirectional fiber orientation, termed “unidirectional tapes structure” for the fabrication of high performance composites. This novel technology imparts homogeneity, uniformity, orientation and thermal stability in unidirectional tapes structure that resemble conventional prepreg material. Unidirectional configuration of the tapes structure brings a revolution towards development of cost efficient carbon fiber composites for load bearing structural applications. This paper introduces the concept of tape manufacturing technology and highlights the modifications, optimization, and technological developments carried out to develop unidirectional tapes. The structural parameters that play a significant role in the properties of the high performance composite, such as fiber length, fiber orientation, fiber damage, and uniformity, were assessed during tape manufacturing. The results reveal composites fabricated from unidirectional tape structures with optimum parameters deliver tensile strength and modulus of 1370 ± 22 MPa and 85 ± 4 GPa, respectively.
|
| 6 |
Modellbildung und Simulation des Plasma-Schweißens zur Entwicklung innovativer Schweißbrenner / Modeling and simulation of plasma welding for the development of innovative welding torchesAlaluss, Khaled Ahmed 21 February 2017 (has links) (PDF)
In der vorliegenden Habilitationsarbeit wurden technisch-konstruktive Lösungsansätze basierend auf einem entwickelten strömungs-thermomechanischen/magneto-hydro-dynamischen Simulationsmodell zur Entwicklung/Charakterisierung eines physikalischen Prozesswirkprinzips des betrachteten Mikro- und Hochleistungs- sowie Orbital-Plasma-Schweißprozesses und dessen physikalischer Effekte entwickelt. Dabei wurden die differenten Einflussgrößen beim Plasmaschweißprozess erfasst, analysiert und ihre Wirkung auf Schweißprozessverhalten und Brennerkonstruktion charakterisiert. Die damit gewonnenen Ergebnisse wurden zur werkstofflichen, technisch-konstruktiven Entwicklung der Brennerkopfmodelle hinsichtlich der Ausführungsgeometrien des Prozessgaszuführungs- und Brennerkühlsystems genutzt.
Im Rahmen des erarbeiteten thermomechanischen Simulationsmodells wurden die beim Plasma-Auftragschweißen von Verbundbauteilen auftretenden Temperaturfelder, Verformungen und Eigenspannungen vorausbestimmt, untersucht und analysiert. Mittels des erarbeiteten Simulationsmodells wurden werkstoffliche, konstruktive und fertigungstechnische Maßnahmen zur Minimierung/Beeinflussung schweißbedingter Verformungen und Eigenspannungen simulativ untersucht und bewertet. / In this work, technical and constructive solutions were developed based on simulation models (process and structural) for fluid mechanical, thermomechanical and magneto-hydrodynamic effects. The simulation process included improving and characterising the physical operating principles for micro plasma welding, high performance plasma welding and orbital plasma welding. Also, the physical effects for the above plasma welding processes were studied and analysed. From these different physical properties of the parameters for the plasma welding processes, and their effects on plasma welding process behaviour and torch design were analysed and characterised. The results were used for the development and construction of plasma welding torch models, which included material selection and geometrical design such as, process gas supply design, torch cooling system design, and other related torch designs.
By developing the thermomechanical simulation model, deformations and residual stresses that were generated by heating during the plasma welding process were investigated and analysed. The developed thermomechanical model
included material, structural and welding specifications such as buffering and preheating. Simulations utilizing this model were used in order to reduce the residual stresses and deformations of the welded components.
|
| 7 |
Modellbildung und Simulation des Plasma-Schweißens zur Entwicklung innovativer SchweißbrennerAlaluss, Khaled Ahmed 21 February 2017 (has links)
In der vorliegenden Habilitationsarbeit wurden technisch-konstruktive Lösungsansätze basierend auf einem entwickelten strömungs-thermomechanischen/magneto-hydro-dynamischen Simulationsmodell zur Entwicklung/Charakterisierung eines physikalischen Prozesswirkprinzips des betrachteten Mikro- und Hochleistungs- sowie Orbital-Plasma-Schweißprozesses und dessen physikalischer Effekte entwickelt. Dabei wurden die differenten Einflussgrößen beim Plasmaschweißprozess erfasst, analysiert und ihre Wirkung auf Schweißprozessverhalten und Brennerkonstruktion charakterisiert. Die damit gewonnenen Ergebnisse wurden zur werkstofflichen, technisch-konstruktiven Entwicklung der Brennerkopfmodelle hinsichtlich der Ausführungsgeometrien des Prozessgaszuführungs- und Brennerkühlsystems genutzt.
Im Rahmen des erarbeiteten thermomechanischen Simulationsmodells wurden die beim Plasma-Auftragschweißen von Verbundbauteilen auftretenden Temperaturfelder, Verformungen und Eigenspannungen vorausbestimmt, untersucht und analysiert. Mittels des erarbeiteten Simulationsmodells wurden werkstoffliche, konstruktive und fertigungstechnische Maßnahmen zur Minimierung/Beeinflussung schweißbedingter Verformungen und Eigenspannungen simulativ untersucht und bewertet. / In this work, technical and constructive solutions were developed based on simulation models (process and structural) for fluid mechanical, thermomechanical and magneto-hydrodynamic effects. The simulation process included improving and characterising the physical operating principles for micro plasma welding, high performance plasma welding and orbital plasma welding. Also, the physical effects for the above plasma welding processes were studied and analysed. From these different physical properties of the parameters for the plasma welding processes, and their effects on plasma welding process behaviour and torch design were analysed and characterised. The results were used for the development and construction of plasma welding torch models, which included material selection and geometrical design such as, process gas supply design, torch cooling system design, and other related torch designs.
By developing the thermomechanical simulation model, deformations and residual stresses that were generated by heating during the plasma welding process were investigated and analysed. The developed thermomechanical model
included material, structural and welding specifications such as buffering and preheating. Simulations utilizing this model were used in order to reduce the residual stresses and deformations of the welded components.
|
| 8 |
TU-Spektrum 1/2007, Magazin der Technischen Universität ChemnitzSteinebach, Mario, Häckel-Riffler, Christine, Brabandt, Antje, Mahler, Janine, Chlebusch, Michael, Doriath, Thomas, Leidholdt, Nicole, Facius, Marlies 10 April 2007 (has links) (PDF)
zweimal im Jahr erscheinende Zeitschrift über aktuelle Themen der TU Chemnitz, ergänzt von Sonderheft(en)
|
| 9 |
TU-Spektrum 1/2007, Magazin der Technischen Universität ChemnitzSteinebach, Mario, Häckel-Riffler, Christine, Brabandt, Antje, Mahler, Janine, Chlebusch, Michael, Doriath, Thomas, Leidholdt, Nicole, Facius, Marlies 23 April 2007 (has links) (PDF)
zweimal im Jahr erscheinende Zeitschrift über aktuelle Themen der TU Chemnitz, ergänzt von Sonderheft(en)
neue Archivierung, da verbesserte Bildqualität
|
| 10 |
TU-Spektrum 1/2007, Magazin der Technischen Universität ChemnitzSteinebach, Mario, Häckel-Riffler, Christine, Brabandt, Antje, Mahler, Janine, Chlebusch, Michael, Doriath, Thomas, Leidholdt, Nicole, Facius, Marlies 10 April 2007 (has links)
zweimal im Jahr erscheinende Zeitschrift über aktuelle Themen der TU Chemnitz, ergänzt von Sonderheft(en)
|
Page generated in 0.131 seconds