Дисертації з теми "Microstructured"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Microstructured.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Microstructured".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Wan, Yu Shan Susanna. "Zeolite microstructured reactors." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405836.
Повний текст джерела
2
Jin, Chuhang. "Microstructured Terahertz Fiber." Thesis, KTH, Tillämpad fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265667.
Повний текст джерела
3
Aqil, Sanaa. "Wetting of microstructured surfaces." Thesis, Nottingham Trent University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431843.
Повний текст джерела
4
Suhailin, Fariza Hanim Binti. "Microstructured silicon fibre devices." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/405516/.
Повний текст джерелаАнотація:
Silicon photonics is an advanced platform for the development of compact integrated optical devices. Major breakthroughs such as light generation, signal amplification and high-speed modulation have been demonstrated in silicon waveguides due to their large nonlinear effects. Recent fabrication methods have enabled the infiltration of crystalline and amorphous semiconductor materials inside silica capillaries to combine the excellent optoelectronic properties of silicon with the waveguiding capabilities of fibres. This new class of waveguide maintains many of the advantageous properties of commercial silica glass fibres such as robustness and flexibility, as well as offering the potential for seamless integration within existing networks. Furthermore, the silicon fibre platform can also be post-processed to fabricate novel micron-scale devices, beyond what is achievable in their planar counterparts. In this thesis, two forms of fibre-based semiconductor devices have been investigated; tapered silicon core waveguides and whispering gallery mode microresonators. These devices were fabricated as a unique approach to enhance the light-matter interactions for the development of all-optical signal processing devices. Improvements in the crystallinity and the optical transmission properties of polysilicon core fibres were achieved via fibre tapering, enabling the first demonstration of nonlinear propagation in this material. Moreover, different forms of resonators were fabricated from amorphous and polycrystalline silicon core fibres. Ultrafast all-optical modulation via the Kerr nonlinearity is demonstrated at picoseconds switching speeds using pure amorphous silicon resonators and in hybrid silica glass and polysilicon core resonators.
5
Dubert, Diana Cristina. "Catalyser production with microstructured components." Doctoral thesis, Universitat Rovira i Virgili, 2012. http://hdl.handle.net/10803/79151.
Повний текст джерелаАнотація:
La tesis describe un método completamente nuevo sobre la aplicación de este micro-tecnología en la producción de los catalizadores, específicamente NH4-dawsonite. Las soluciones acuosas utilizadas para precipitar el material se define como nonahidrato nitrato de aluminio y carbonato de amonio. La preparación del mineral análogo se realizó por primera vez dentro de un micro-mezclador de acero inoxidable (CPMM 1200/8) con un volumen de 78μl y un principio de mezcla “split-recombine”, optimizando los parámetros del proceso para un tiempo de producción continuo que, en este caso, es significativamente afectado por la obstrucción del micro-canal. Además, la síntesis se realizó dentro del micro-sistema presurizado y se han propuesto otro tres diferentes geometrías del micro-canal: en forma de T de acero inoxidable, el poly (metylmetacrylate) (PMMA) spilt-recombine del micromixer Caterpillar y en forma de Y la unión de PMMA dos regímenes diferentes de mezcla (perfecta (spilt-recombine) / imperfecto (T / Y en forma de microsistemas)) con el objetivo de minimizar la obstrucción del canal. El enfoque de unión-Y se ha demostrado ser la mejor alternativa para reducir al mínimo la deposición de partículas en la pared del canal, lo que implica un mejor control del fenómeno de obstrucción, al estar totalmente eliminado. Esto representa un paso adelante en el proceso de intensificación con beneficios en la industria. Al superar este paso, la posibilidad de transferir esta nueva tecnología en la industria es cada vez más tangible a convertirse en realidad.The thesis presents a new approach regarding the application of microtechnology in production of catalysts, specifically NH4-dawsonite by using microreactor technology. The aqueous solutions used to precipitate the material were defined as aluminium nitrate nonahydrate and ammonium carbonate. The mineral analogue preparation was first held within a 78μl volume split-recombine stainless steel micromixer (CPMM 1200/8 mixer) by optimizing the process parameters for a continuous time of production which in the present case is significantly affected by the channel clogging. Further, the synthesis was carried out within a pressurized micro-system and different geometries of the microchannel: T-shaped stainless steel, poly(metylmetacrylate) (PMMA) spilt-recombine Caterpillar micromixer and Y-shaped PMMA junction with two different mixing regimes (perfect (spli-recombine)/imperfect (T/Y-shaped microsystem)) with the aim of minimizing the clogging. The Y-junction approach was demonstrated to be a great alternative for minimizing the particle deposition on channel’s wall, clogging phenomenon being totally removed. This represents a significant step forward in process intensification with benefits within the industry. Over passing this step the possibility to transfer this new technology into industry is more and more tangible to become reality.
6
Ager, C. D. "Plasmons in microstructured semiconductor 2DEGs." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385904.
Повний текст джерела
7
Li, Qingquan. "Microstructured optical fibres in chalcogenide glass." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602615.
Повний текст джерелаАнотація:
Chalcogenide glasses offer transmission windows within the far-visible, near- and midinfrared (IR) range. They exhibit potentially excellent linear and large non linear optical properties, photosensitivity and their low phonon energies are conducive to efficient dopant rare earth transitions. These properties enable many potential infrared applications: large-scale optics; fibreoptics; integrated optics; optical imaging; optical data storage and all-optical switching. Two lines of experimental work were followed in this project based on chalcogenide glasses, as below: (1) Antimony was used to replace arsenic, to fOIm the ternary Ge-Sb-Se glass system. Nine compositions of Ge-Sb-Se glasses were synthesised and characterised to reveal their glass forming abilities, thermal properties and optical properties. Glass pairs, with close thermal propeIties and relatively high refractive index contrast, were developed for fabricating core-clad. structure step index fibre and micro structured optical fibres (MOFs). (2) Fabrication of an all-solid chalcogenide glass micro structured fibre (MOF), which was designed as a mimic of the holey suspended structure silica MOF, was canied out. A cane-drawing technique and a real-time contactless diameter monitor of the chalcogenide canes were developed to improve the precision of the fabrication. Stacking equipment was designed to improve the technique of the chalcogenide preform stacking.
8
Chang, Jean H. "Tunable wettability of microstructured polypyrrole films." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62526.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 85-90).
This thesis presents the development of the conducting polymer polypyrrole as a viable material for applications requiring switchable wettability. A fabrication procedure that produces robust microstructured polypyrrole (PPy) that quickly and reversibly switches between the superhydrophobic and superhydrophilic states is discussed. The polymer is doped with perfluorooctanesulfonate ions which diffuse in and out of the film upon an electric stimulus, causing a change in the material's surface energy. The effect of changing different deposition parameters on the switchable wettability of the polymer is also investigated. A post-deposition thermal treatment that improves the electrochemical properties of polypyrrole is presented. Finally, a device that allows for the in situ wettability switch of PPy is developed, eliminating the need for polypyrrole to be immersed in an electrolyte in order to switch between wetting states. A wettability gradient created on the surface of PPy using the device is used to demonstrate a possible application requiring induced fluid movement. Electrochemical techniques are used to synthesize and characterize the polymers, and scanning electron microscopy is used to examine the surface morphology of the films.
by Jean H. Chang.
S.M.
9
Constantinou, A. "CO2 absorption in microstructured membrane reactors." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1348316/.
Повний текст джерелаАнотація:
The objective of this work is to study experimentally and theoretically novel multiphase microreactors and characterize them in relation to hydrodynamics and mass transfer, in order to evaluate, understand and improve their performance. In order to achieve this CO2 absorption in sodium hydroxide and amine solutions an example of a fast gas-liquid reaction has been investigated in a single microstructured metallic mesh reactor, CRL reactor, PTFE single channel membrane reactor and the silicon nitride mesh reactor. CO2 absorption in sodium hydroxide solution was initially studied experimentally and theoretically in a metal microstructured mesh reactor. The differential mass balances to describe the concentration profiles of components in the three domains (gas/membrane/liquid), were solved with Comsol Multiphysics (modeling software for finite element analysis of partial differential equations). The model indicated that the carbon dioxide is consumed within few microns from the gas – liquid interface, and the dominant resistance for mass transfer is located in the mesh because it is wetted by the liquid reactant. In order to overcome the limitation of the extra resistance to the mass transfer in the metallic mesh, PTFE membranes were used in the single channel reactor, which are considered as hydrophobic to aqueous solutions of NaOH and amines. Monoethanolamine solution (MEA) absorbed more CO2 than diethanolamine (DEA) since the reaction rate constant for MEA is higher than DEA. 8 channel (PTFE) microreactor showed much higher CO2 removal efficiency than the metallic mesh microreactor. Furthermore the model indicated partial-wetting of the PTFE membrane when NaOH solution was used as an absorbent. In order to enhance mass transfer staggered herringbones were used on the floor of the liquid side of the single channel PTFE microreactor. No enhancement of mass transfer was observed with the use of staggered herringbones. A possible reason for that is that a limit for the fast second-order reaction is reached for enhancement and that the apparent reaction rate is independent from mass transfer for our case, or that the herringbones are far away from the reaction zone and cannot create the appropriate stirring for enhancement. In order to increase throughput, carbon dioxide absorption in sodium hydroxide solution was performed in the metallic mesh ‘scale-out’ reactor (with 4 meshes). CO2 removal efficiency for the ‘scale-out’ reactor was significantly lower than the single mesh reactor, which is probably due to breakthrough of liquid in the gas phase (stagnant liquid) or uneven flow distribution in each plate of the ‘scale-out’ reactor. Finally a silicon nitride mesh reactor developed by Bayer Technology Services and FluXXion was used for CO2 absorption in aqueous solutions of NaOH and DEA. The silicon nitride mesh reactor showed better performance than the PTFE single channel reactor, the metallic 8 channel reactor and the CRL mesh reactor when NaOH was used, due to the very thin membrane of 1 μm thickness, which makes the resistance to mass transfer very small.
10
Otero, Gruer Fermin. "Multiscale numerical modelling of microstructured reinforced composites." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/392625.
Повний текст джерелаАнотація:
Most of the existing materials around us can be considered composite materials, since they are composed by several phases or components at certain spatial scale. The physical and chemical properties of composites, as occurs with structures composed by two or more materials, is defined by the response provided by their constituents. Therefore, a good characterization of the composite requires considering the performance of its components. In the last decades, several methods have been proposed with this approach to characterize composite materials, most of them based on multiscale techniques.
Nowadays, multiscale homogenization analysis is a popular topic in the simulation of composite materials. This is because the complexity of new composites demands of advanced analysis techniques for their correct characterization, and thanks to the continuous increase of computational capacity. However, the computational cost when multiscale procedures are taken to the non-linear range and are applied to real-size structures is still excessively high. In this context, this work presents a comprehensive homogenization formulation for an efficient non-linear multiscale modeling of composite structures.
The development of a composite multiscale constitutive model is addressed from two different homogenization approaches. The first one corresponds to a phenomenological homogenization procedure for the non-linear analysis of carbon nanotubes reinforced composites. The second one is a general two-scale homogenization procedure to analyze three-dimensional composite structures.
Carbon nanotubes (CNTs) have been regarded as ideal reinforcements for high-performance composites. The formulation developed takes into account explicitly the performance of the interface between the matrix and the CNTs. The load is transferred to the nanotubes through the considered interface. The composite non-linear behavior results from the non-linearities of its constituents, and in case of interface damage, it also becomes non-linear the law defined to couple the interface with the CNTs. The formulation is validated studying the elastic response and non-linear behavior of several composites.
In the context of multiscale homogenization, a first-order and an enhanced-first-order formulation is developed. The results obtained for laminate composites using the first-order formulation are compared with other microscopic formulations, showing that the homogenization method is an excellent alternative when microstructural effects must be taken into account. Then, a strategy to conduct non-linear multiscale analysis in an efficient way is proposed. The procedure conserves the dissipated energy through the scales and is mesh independent. The analysis of academic examples is used to show the capacity of the non-linear strategy. Finally, the simulation of an industrial composite component proves the performance and benefits of the non-linear homogenization procedure developed.La obra de fábrica es un material de construcción tradicional que ha sido utilizado a lo largo de la historia y que sigue siendo utilizado hoy en día. La obra de fábrica constituye la principal técnica de construcción adoptada en estructuras históricas, y una comprensión profunda de su comportamiento es de vital importancia para la conservación de nuestro patrimonio cultural. A pesar de su amplio uso, la obra de fábrica ha sido utilizada frecuentemente adoptando un enfoque empírico, debido a un escaso conocimiento del comportamiento mecánico complejo de este tipo de material compuesto. Los métodos numéricos avanzados son herramientas atractivas para entender y predecir el comportamiento de la obra de fábrica hasta su fallo, permitiendo estimar la resistencia residual y la seguridad de las estructuras. Durante los últimos años, han sido propuestos diferentes modelos computacionales, basados bien en una micro-modelización completa de los constituyentes del material (ladrillos y juntas de mortero), o bien en macro-modelos fenomenológicos. A partir de estos dos enfoques, los métodos de homogenización computacional han emergido recientemente como una herramienta prometedora que puede combinar las ventajas de la micro- y macro-modelización. El problema se divide en dos pasos: la escala estructural se trata como un medio homogéneo equivalente, mientras el comportamiento complejo de la microestructura heterogénea se tiene en cuenta mediante la resolución de un problema micro-mecánico reconducible a una muestra representativa de la microestructura. El objetivo de esta investigación es el desarrollo de una técnica de homogenización computacional multi-escala para el análisis de estructuras de obra de fábrica sometidas a cargas horizontales cuasi-estáticas que actúan en el plano y fuera del plano. Se adopta la teoría clásica del medio continuo de Cauchy en ambas las escalas, utilizando así la homogeneización computacional del primer orden. Debido a la naturaleza frágil de los componentes de la obra de fábrica, el estudio contempla también el problema de la localización de la deformación en el marco del enfoque numérico de fisura distribuida. En este contexto, la presente investigación propone una extensión de la regularización basada en la energía de fractura para el problema de homogenización en dos escalas, permitiendo el uso de la homogenización computacional del primer orden en problemas que implican la localización de la deformación. El método se plantea en primer lugar para el caso continuo general, y a continuación se aplica al análisis de muros de corte cargados en su plano y hechos de fábrica de ladrillos con aparejo periódico. Posteriormente, el método se extiende al caso de estructuras tipo placa para el análisis de muros de obra de fábrica cargados fuera de su plano. Para este propósito, se desarrolla una nueva técnica de homogenización basada en la teoría de placas gruesas. En ambos los casos de carga en el plano y fuera del plano, la precisión del método propuesto se valida mediante la comparación con ensayos experimentales y análisis de micro-modelización. También se validan las propiedades de regularización. Los resultados obtenidos muestran cómo la homogeneización computacional pueda resultar una herramienta válida para una evaluación precisa de la respuesta estructural de las estructuras de obra de fábrica, teniendo en cuenta el comportamiento complejo de la micro-estructura.
11
Issa, Nader. "Modes and propagation in microstructured optical fibres." University of Sydney. Physics and Optical Fibre Technology Centre, 2005. http://hdl.handle.net/2123/613.
Повний текст джерелаАнотація:
Microstructured optical fibres (MOFs), also commonly called photonic crystal fibres or holey fibres, describe a type of optical fibre in which continuous channels of (typically) air run their entire length. These `holes' serve to both confine electromagnetic waves within the core of the fibre and to tailor its transmission properties. In order to understand and quantify both of these functions, a new computational algorithm was developed and implemented. It solves for the eigenvalues of Maxwell's wave equations in the two-dimensional waveguide cross-section, with radiating boundary conditions imposed outside the microstructure. This yields the leaky modes supported by the fibre. The boundary conditions are achieved exactly using a novel refinement scheme called the Adjustable Boundary Condition (ABC) method. Two implementations are programmed and their computational efficiencies are compared. Both use an azimuthal Fourier decomposition, but radially, a finite difference scheme is shown to be more efficient than a basis function expansion. The properties of the ABC method are then predicted theoretically using an original approach. It shows that the method is highly efficient, robust, automated and generally applicable to any implementation or to other radiating problems. A theoretical framework for the properties of modes in MOFs is also presented. It includes the use of the Bloch-Floquet theorem to provide a simpler and more efficient way to exploit microstructure symmetry. A new, but brief study of the modal birefringence properties in straight and spun fibres is also included. The theoretical and numerical tools are then applied to the study of polymer MOFs. Three types of fibres are numerically studied, fabricated and characterised. Each is of contemporary interest. Firstly, fabrication of the first MOFs with uniformly oriented elliptical holes is presented. A high degree of hole ellipticity is achieved using a simple technique relying on hole deformation during fibre draw. Both form and stress-optic birefringence are characterized over a broad scaled-wavelength range, which shows excellent agreement with numerical modelling. Secondly, an analysis of leaky modes in real air core MOFs, fabricated specifically for photonic band gap guidance, is then used to identify alternative guiding mechanisms. The supported leaky modes exhibit properties closely matching a simple hollow waveguide, weakly influenced by the surrounding microstructure. The analysis gives a quantitative determination of the wavelength dependent confinement loss of these modes and illustrates a mechanism not photonic band gap in origin by which colouration can be observed in such fibres. Finally, highly multimode MOFs (also called `air-clad' fibres) that have much wider light acceptance angles than conventional fibres are studied. An original and accurate method is presented for determining the numerical aperture of such fibres using leaky modes. The dependence on length, wavelength and various microstructure dimensions are evaluated for the first time for a class of fibres. These results show excellent agreement with published measurements on similar fibres and verify that bridge thicknesses much smaller than the wavelength are required for exceptionally high numerical apertures. The influence of multiple layers of holes on the numerical aperture and capture efficiency are then presented. It shows that a substantial increase in both these parameters can be achieved for some bridge thicknesses. Simple heuristic expressions for these quantities are given, which are based on the physical insight provided by the full numerical models. The work is then supported by the first fabrication attempts of large-core polymer MOFs with thin supporting bridges. These fibres exhibit relatively high numerical apertures and show good agreement with theoretical expectations over a very wide scaled-wavelength range.
12
Norton, Jamie Christine Sharp. "Synthesis and electrochemical studies in microstructured media." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1211387489/.
Повний текст джерела
13
Yang, Zhugen. "3D-Microstructured Protein Chip for Cancer Diagnosis." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00780192.
Повний текст джерелаАнотація:
Protein microarrays are becoming powerful tools to screen and identify tumor markers for cancer diagnosis, because of the multiplex detection and minute volume of sample requirement. Due to the diversity and variation in different cancers, no single tumor marker is sensitive and specific enough to meet strict diagnostic criteria. Therefore, a combination of tumor markers is required to increase sensitivity and to establish distinct patterns to increase specificity. To obtain reliable tests, the development of reproducible surface chemistry and immobilization procedure are crucial steps in the elaboration of efficient protein microarrays. In this thesis, 3D micro-structured glass slides were functionalized with various surface chemistries like silane monolayer (amino, epoxy and carboxy), and polymer layers of Jeff amine, chitosan, carboxymethyl dextran (CMD), maleic anhydride-alt-methyl vinyl ether copolymer (MAMVE) for physical adsorption or covalent binding with proteins. Surface characterizations, such as X-ray photoelectron spectroscopy (XPS) and Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), confirmed the monolayer/polymer grafting on the glass slides. Colorimetric assay for determining amine density of three aminated surfaces demonstrated that APDMES had more grafting density than Jeffamine and chitosan. Contact angle measurements show that polymer surfaces were more hydrophilic than monolayer surfaces due to the increasing dosages of polar functional groups. Moreover, the parameters such as additives and pH of spotting buffer, probe concentration, blocking procedures etc, were optimized for tumor marker detection. Under the optimized conditions, antibody microarrays were validated with purified tumor antigens. The best analytical performances obtained for each tumor antigen tested were strongly dependent on functionalized surfaces, e.g. MAMVE exhibited best analytical performances for CEA andHsp60 while NHS leads to best results for PDI and CA19-9. Besides, the implemented antibody microarrays were applied to tumor marker detection from colorectal cancer sera. This evaluation shows the interest to combine several tumor markers on the same surface and the combination of tumor markers on their specific surface lead to remarkably increase the positive responses of tested cancer sera (even up to 100 %). A second type of microarrays (tumor-associated antigens - TAA microarrays) was designed to discriminate breast cancer patients from healthy donors through the detection of tumor autoantibodies. This study included a cohort of 29 breast cancer patients' and 28 healthy donors' sera. A panel of fiveTAAs (Hsp60, p53, Her2, NY-ESO-1 and Hsp70) immobilized on their respective optimized surface chemistry allowed to specifically detect over 82% of breast cancer patients.
14
Hisatomi, Makiko. "A theoretical study of zoned microstructured fibre." Thesis, University of Essex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433599.
Повний текст джерела
15
Voyce, Christopher Jonathan. "The mathematical modelling of microstructured optical fibres." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433931.
Повний текст джерела
16
Ramadan, Mohamed. "Biologically Inspired Microstructured and Nanostructured Polymeric Biomaterials." Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/622.
Повний текст джерелаАнотація:
The precise designs of nature have inspired scientists for centuries to find solutions for complex problems. By studying natural biological systems, scientist are able to identify patterns, sequences and draw conclusions in order to propose possible solutions. The interplay between chemistry and structure is a common theme in all biological systems. This interplay is often responsible for the function of a given system, for any alterations to this balance leads to undesirable result, namely, systemic malfunction. While chemists have taken advantage of biological systems, nature does not provide answers to every problem or error. Hence, the field of biomaterials combines the beauty of natural design and function with the versatility of chemistry, in the context of this thesis, polymer chemistry. Using elements from nature, polymer chemists are able to modify, functionalize and enhance the function of synthetic systems and offer solutions to complex problems in the biomedical and diagnostic fields. The focus of this thesis centers on the microfabrication of biologically inspired polymeric biomaterials. While the scope of the thesis is broad in the nature of applications considered, given the versatility of the systems developed, the main context or target application remains in the biomedical and diagnostic applications and the intersection of these two domains. The main theme and focus of this thesis is to tailor the chemistry of the system and control the microarchitecture to address relevant biomedical problems. The systems reported here target complex, yet common problems in the field such as: protein fouling on medical devices and diagnostic assays, tissue engineering scaffolding, drug delivery and wet tissue adhesives. Gaining insight into the problems from readily availed biological systems, solutions are proposed using modified polymers for promising biomaterials-based approaches. With special emphasis on tailoring the microarchitecture to specific functions, synthesis, characterization and subsequent microfabrication and testing are reported. Keeping the common theme of controlling the basic polymer chemistry of the system combined with careful microstructure design to address the final application, the thesis is divided into 6 chapters that are grouped to highlight various aspects of the intended applications. Chapters 2-4, address the issue of protein fouling onto medical devices and diagnostic assays. Chapter 5 addresses the microfabrication of tissue engineering scaffolds and drug delivery vehicles. Finally, chapter 6 deals with developing pressure-sensitive wet tissue adhesives. In chapter 2, titled: Reducing Protein Adsorption with Polymer-grafted Hyaluronic Acid Coatings, a novel antifouling coating system based on a thermoresponsive hyaluronic acid polymer hybrid is reported. These materials are designed, synthesized and characterized to possess reversible coating and adhesive properties at relevant physiological temperatures, presenting a nonfouling, hydrophilic layer to the solution. A comparison of the antifouling profile of hyaluronic acid to that of similar polysaccharides, namely dextran, alginate and carboxymethyl cellulose, is performed in chapter 3 under the title: Polymer-grafted Polysaccharide Coatings for Reduced Blood Protein Adsorption. A very promising application of such coatings is then designed to enhance detection accuracy and precision of clinically relevant diagnostic methods, namely enzyme-linked immunosorbent assay (ELISA), which is introduced in chapter 4, titled: Non-Fouling Hyaluronic Acid Coatings for Improved Sandwich ELISA Measurements in Plasma Mixtures. Chapter 5, entitled Microfabricated and Nanofabricated Hyaluronic Acid Constructs: Design and Applications, deals with microfabrication of tissue engineering scaffolds using a novel modified rapid prototyping method for 3D printing of modified hydrogels. Moreover, the potential of micro needles arrays (MNAs) in treating relevant disorders is also investigated. The final chapter of this thesis, Chapter 6: Microfabricated Gecko-inspired Microfibers for Enhanced Wet Tissue Adhesion, explores the wet adhesive properties of mussel-inspired wet adhesives coatings of gecko-inspired polyurethane microfibers.
17
Fronk, Ryan. "Dual-side etched microstructured semiconductor neutron detectors." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35405.
Повний текст джерелаАнотація:
Doctor of PhilosophyDepartment of Mechanical and Nuclear Engineering
Douglas S. McGregor
Interest in high-efficiency replacements for thin-film-coated thermal neutron detectors led to the development of single-sided microstructured semiconductor neutron detectors (MSNDs). MSNDs are designed with micro-sized trench structures that are etched into a vertically-oriented pvn-junction diode, and backfilled with a neutron converting material, such as 6LiF. Neutrons absorbed by the converting material produce a pair of charged-particle reaction products that can be measured by the diode substrate. MSNDs have higher neutron-absorption and reaction-product counting efficiencies than their thin-film-coated counterparts, resulting in up to a 10x increase in intrinsic thermal neutron detection efficiency. The detection efficiency for a single-sided MSND is reduced by neutron streaming paths between the conversion-material filled regions that consequently allow neutrons to pass undetected through the detector. Previously, the highest reported intrinsic thermal neutron detection efficiency for a single MSND was approximately 30%. Methods for double-stacking and aligning MSNDs to reduce neutron streaming produced devices with an intrinsic thermal neutron detection efficiency of 42%. Presented here is a new type of MSND that features a complementary second set of trenches that are etched into the back-side of the detector substrate. These dual-sided microstructured semiconductor neutron detectors (DS-MSNDs) have the ability to absorb and detect neutrons that stream through the front-side, effectively doubling the detection efficiency of a single-sided device. DS-MSND sensors are theoretically capable of achieving greater than 80% intrinsic thermal neutron detection efficiency for a 1-mm thick device. Prototype DS-MSNDs with diffused pvp-junction operated at 0-V applied bias have achieved 53.54±0.61%, exceeding that of the single-sided MSNDs and double-stacked MSNDs to represent a new record for detection efficiency for such solid-state devices.
18
Fronk, Ryan G. "Dual-side etched microstructured semiconductor neutron detectors." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35426.
Повний текст джерелаАнотація:
Doctor of PhilosophyDepartment of Mechanical and Nuclear Engineering
Douglas S. McGregor
Interest in high-efficiency replacements for thin-film-coated thermal neutron detectors led to the development of single-sided microstructured semiconductor neutron detectors (MSNDs). MSNDs are designed with micro-sized trench structures that are etched into a vertically-oriented pvn-junction diode, and backfilled with a neutron converting material, such as ⁶LiF. Neutrons absorbed by the converting material produce a pair of charged-particle reaction products that can be measured by the diode substrate. MSNDs have higher neutron-absorption and reaction-product counting efficiencies than their thin-film-coated counterparts, resulting in up to a 10x increase in intrinsic thermal neutron detection efficiency. The detection efficiency for a single-sided MSND is reduced by neutron streaming paths between the conversion-material filled regions that consequently allow neutrons to pass undetected through the detector. Previously, the highest reported intrinsic thermal neutron detection efficiency for a single MSND was approximately 30%. Methods for double-stacking and aligning MSNDs to reduce neutron streaming produced devices with an intrinsic thermal neutron detection efficiency of 42%. Presented here is a new type of MSND that features a complementary second set of trenches that are etched into the back-side of the detector substrate. These dual-sided microstructured semiconductor neutron detectors (DS-MSNDs) have the ability to absorb and detect neutrons that stream through the front-side, effectively doubling the detection efficiency of a single-sided device. DS-MSND sensors are theoretically capable of achieving greater than 80% intrinsic thermal neutron detection efficiency for a 1-mm thick device. Prototype DS-MSNDs with diffused pvp-junction operated at 0-V applied bias have achieved 53.54±0.61%, exceeding that of the single-sided MSNDs and double-stacked MSNDs to represent a new record for detection efficiency for such solid-state devices.
19
Issa, Nader A. "Modes and propagation in microstructured optical fibres." Connect to full text, 2005. http://hdl.handle.net/2123/613.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Sydney, 2005.Title from title screen (viewed 21 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Optical Fibre Technology Centre, School of Physics. Includes bibliographical references. Also available in print form.
20
Biancalana, Fabio. "Modelling of nonlinear effects in microstructured fibres." Thesis, University of Bath, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413912.
Повний текст джерела
21
Mpuhlu, Batsho. "Vapour phase dehydrogenation of cyclohexane on microstructured reactors." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/8661.
Повний текст джерелаАнотація:
The work that is described in this thesis forms part of the research and development projects at InnoVenton: NMMU Institute of Chemical Technology in collaboration with Sasol Technologies. The broader view of the project was testing on the so-called “Small Production Platforms” (SPP’s). In particular the main aim of this study was to investigate the effect of micro-structuring on the heterogeneous catalysed, vapour-phase oxidative dehydrogenation of cyclohexane in the presence of air. Ground work studies were done to provide a proper comparison of the micro-structured reactor with a traditional fixed-bed reactor. These included evaluation of a proper vanadium pyrophosphate catalyst for the reaction, testing of reaction parameters for the oxidative dehydrogenation reaction on a fixed-bed reactor and lastly comparing the performance of the micro-structured reactor to that of the fixed-bed reactor Various vanadium pyrophosphate catalysts that were tested for activity included: bulk (VO)2P2O7, bulk (VO)2P2O7 promoted with Fe, (VO)2P2O7 supported on -Al2O3 and Fe promoted (VO)2P2O7 supported on -Al2O3. These catalysts showed significant differences in TOF, however it was not conclusive from the results whether these differences may be traced to increased activity for dehydrogenation for different catalysts since all reactions were run under conditions of oxygen deficiency. It is, however, clear that Fe promotion significantly increase activity, irrespective of the relative degrees of oxidative dehydrogenation and normal dehydrogenation. The Fe promoted catalyst was further tested for long term stability in-view of using it as the catalyst in the micro-structured reactor. These studies showed the catalyst to have a high degree of stability with minimal structural changes under the reaction conditions used. Various response surface models describing the variation in each of the cyclohexane conversion, cyclohexene selectivity, and benzene selectivity, respectively when changing reaction condition, were derived by means of multiple regression. To obtain some idea of the degree and nature of the normal dehydrogenation reaction, the amount of deficit oxygen was estimated from the measured results for cyclohexane conversion and cyclohexene and benzene selectivities. These estimated values were also modelled as described above. The regression models were used to interpret specific trends in the responses for the oxidative dehydrogenation of cyclohexane and account for the oxygen deficit in the system. The performance of a fixed bed tubular reactor (FBR) and micro-structured sandwich reactor (MSSR) were compared over an Fe promoted vanadium pyrophosphate. Reactor performance was evaluated by varying specific reaction conditions (temperature and space velocity). Subsequently the turn-over frequencies, conversion and selectivities from the two reactors were compared. The conversion achieved in the micro-structured reactor was observed to be significantly higher than that achieved in the fixed-bed reactor at all reaction parameters. This is despite the fact that the total amount of catalyst in the micro-structured reactor is approximately 5 times less than that used in the fixed bed reactor. In addition, the contact time (1/MHSV) in the micro-structured reactor is also significantly shorter than in the fixed-bed reactor.
22
Khatri, Bilal [Verfasser], and Thomas [Akademischer Betreuer] Hanemann. "Rapid prototyping of functional microstructured polymer-based composites." Freiburg : Universität, 2018. http://d-nb.info/1187133248/34.
Повний текст джерела
23
Furusawa, Kentaro. "Development of rare-earth doped microstructured optical fibres." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/15481/.
Повний текст джерелаАнотація:
This thesis describes the development of novel optical fibres, microstructured optical fibres (MOFs), and demonstrates device applications based on these structures. A particular emphasis is made on incorporating rare-earth ions within these fibres in order to realise novel active devices. Together with the development of the fabrication technique, characterisation and applications of these radically different fibre types are presented. First, the fabrication techniques of MOFs, which heavily rely upon fibre drawing, are studied. A mathematical model developed for the capillary drawing process is experimentally examined. Good agreement is obtained whilst it is also found that the model provides useful physical insights for determining the fibre draw parameters even for MOFs with complex geometries. Details of the fabrication techniques developed to optimise fibre structures are also presented. Transmission properties of highly nonlinear MOFs are then studied experimentally. It is found that the transmission losses are strongly influenced by the core dimensions due to the high Rayleigh scattering coefficient that originates from the holey cladding. A simple model is used to explain the observations. In addition, a continuous effort towards reducing OH-induced losses of this fibres type is outlined. Rare-earth doped highly nonlinear MOFs are fabricated and characterised. Then, three device demonstrations are carried out for the first time. These include a mode-locked ytterbium doped MOF laser, a nonlinear amplifier based on an ytterbium doped MOF, and a continuous wave erbium doped MOF laser with a very low threshold and high efficiency. Using the ytterbium doped MOF, wide tunability of ultrashort pulses from 1µm to 1.58µm is demonstrated using the soliton self frequency shift effect. For the erbium doped MOF, a pump power threshold of 0.5mW and a slope efficiency of 57% are demonstrated. Novel cladding pumped fibres, air clad MOFs, which use a conventional inner cladding and a holey outer cladding, are developed aiming at improved performance of cladding pumped fibre lasers. Wide tunability over 110nm and pure three level operation at 980nm of ytterbium doped cladding pumped fibre lasers are demonstrated. Finally, the fabrication and characterisation of large mode area microstructured fibres (LMA-MOFs) are described, and a comparison with conventional counterparts is made in terms of bend losses and corresponding effective mode areas. The results show that a slight refractive index difference introduced in the core region of this fibre type strongly modifies its waveguide characteristics. By applying this knowledge, a novel ytterbium doped cladding pumped fibre, which uses different sizes of air holes to define the inner and outer cladding, is developed. A continuous wave output power in excess of 1W is obtained. Results concerning various forms of pulsed laser operation using this fibre are presented and future possibilities are discussed.
24
Poletti, Francesco. "Direct and inverse design of microstructured optical fibres." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/47759/.
Повний текст джерелаАнотація:
Microstructured optical fibres, where an arrangement of air holes running longitudinally along the fibre guides light in either a solid or a hollow core, have created new opportunities in diverse areas of science and technology. Applications range from the generation of supercontinuum light to optical sensing, nonlinear telecom devices and the generation and delivery of extremely high optical powers. Photonic bandgap fibres, allowing light guidance in a hollow core, are also extensively studied. The main issues preventing accurate simulations of the properties of fabricated fibres are identified and addressed. An ideal, accurate representation of a realistic fibre is then proposed and employed to obtain fundamental scaling rules and to study the interactions between air guided and surface guided modes. Anticrossings between these modes in slightly asymmetric structures are identified as the cause for the unusual polarisation effects experimentally observed in these fibres. And finally, guidelines for fabricating fibres with the widest possible operational bandwidth possible are developed and presented.
25
Tusamda, Wakhloo Nayana. "Deformability of cancer cells on 3D microstructured surfaces." Thesis, Mulhouse, 2018. http://www.theses.fr/2018MULH2259.
Повний текст джерелаАнотація:
Cette thèse traite de la compréhension du comportement de différents types de cellules cancéreuses sur des surfaces microstructurées. Nous avons étudié le comportement de cellules issues d’ostéosarcome (SaOS-2) et en particulier leur déformation nucléaire sur des micro-piliers confinés. Nous avons analysé le rôle du cytosquelette, des adhésions focales (AF), du nucléosquelette (LINC et lamin A) et de la chromatine, sur cette déformation. L'actomyosine et les filaments intermédiaires de vimentine jouent un rôle crucial dans l'orchestration de la déformation nucléaire. Nous avons constaté que la disposition des AF était principalement sur les parois latérales des piliers et que la connexion LINC-cytosquelette était essentielle pour le processus de déformation nucléaire contrairement à la lamine A. En utilisant des modulations chimio-topographiques des micro-piliers et un modèle de simulation numérique, nous avons démontré que ce sont les forces de traction et non pas les forces de poussée qui permettent la déformation cellulaire et nucléaire des cellules d'ostéosarcome.Nous avons également étudié la déformation nucléaire de SaOS-2 sur des micropiliers en hydrogel présentant différentes chimies et rigidités. Nous avons vu que la morphologie cellulaire, l'organisation de l'actine et le comportement des AF étaient modulés par la chimie et la mécanique du substrat. Pour explorer le rôle de l’origine du cancer, nous avons examiné le comportement de divers carcinomes du côlon sur des microtopographies différentes et constaté que les cancers d'origine épithéliale étaient moins sensibles à la microtopographie que les cellules cancéreuses d'origine mésenchymateuse. Par contre, leur comportement était affecté de manière plus visible sur des grandes cavités plus proches en termes de taille de celles des cryptes et villosités intestinalesThis thesis deals with understanding behaviour of different cancer cell types on microstructured topography. We studied the behaviour of osteosarcoma cell line (SaOS-2) on confined micropillar structures and in particular their nuclear deformation. We analysed the role of the cytoskeleton, focal adhesions (FAs), nucleoskeleton (LINC and lamin A) and chromatin in SaOS-2 deformation on micropillar topography. Actomyosin and vimentin intermediate filament were shown to play a crucial role in orchestrating nuclear deformation. We found that FAs arrangement was mostly on side walls of pillars and that the LINC-cytoskeletal connection was essential for the nuclear deformation process but not lamin A. Employing chemo-topography modulations of pillars and a computational simulation model we demonstrated that the pulling down forces and not pushing down forces drive the cellular-nuclear deformation in osteosarcoma cells. We also studied the nuclear deformation of SaOS-2 on hydrogel micropillars with different stiffness and chemistry. We saw that cell morphology, actin organization and FAs behaviour was modulated by the substrate mechanics and chemistry. To explore the role of cancer origin, we examined the behaviour of various colon carcinomas on various micro-topographies and found that the epithelial origin cancers are less responsive to microscale topography compared to mesenchymal origin cancerous cells. However, their behaviour was affected on large pits which resembled the intestinal crypt and villi arrangement in terms of size
26
Zhiltsova, Tatiana Vladimirovna. "Injection moulding process optimization for microstructured parts production." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12059.
Повний текст джерелаАнотація:
Doutoramento em Engenharia MecâncicaAo longo das últimas décadas, a micromoldação (u-moldação) por injeção de termoplásticos ganhou um lugar de destaque no mercado de equipamentos eletrónicos e de uma ampla gama de componentes mecânicos. No entanto, quando o tamanho do componente diminui, os pressupostos geralmente aceites na moldação por injeção convencional deixam de ser válidos para descrever o comportamento reológico e termomecânico do polímero na microimpressão. Por isso, a compreensão do comportamento dinâmico do polímero à escala micro bem como da sua caraterização, análise e previsão das propriedades mecânicas exige uma investigação mais alargada. O objetivo principal deste programa doutoral passa por uma melhor compreensão do fenómeno físico intrínseco ao processo da μ-moldação por injeção. Para cumprir com o objetivo estabelecido, foi efetuado um estudo paramétrico do processo de μ-moldação por injeção, cujos resultados foram comparados com os resultados obtidos por simulação numérica. A caracterização dinâmica mecânica das μ-peças foi efetuada com o objetivo de recolher os dados necessários para a previsão do desempenho mecânico das mesmas, a longo prazo. Finalmente, depois da calibração do modelo matemático do polímero, foram realizadas análises estruturais com o intuito de prever o desempenho mecânico das μ-peças no longo prazo. Verificou-se que o desempenho mecânico das μ-peças pode ser significativamente afetado pelas tensões residuais de origem mecânica e térmica. Estas últimas, resultantes do processo de fabrico e das condições de processamento, por isso, devem ser consideradas na previsão do desempenho mecânico e do tempo de serviço das u-moldações.
Over the last decades, microinjection moulding (uIM) of thermoplastics has gained a pertinent place on the market of electronic equipment and a broad range of the mechanical aids. However, when size of components drop to the micro level, the assumptions of the conventional injection moulding cease to describe the complex rheological and thermo-mechanical behavior of the polymer in the microimpression. Therefore, understanding of the polymer flow dynamics at the micro scale as well as characterization, assessment and prediction of the final mechanical properties require a great deal of additional research. The prime objective of this doctoral thesis is to get an insight into the physical phenomena inherent to μIM process. In order to comply with the established objective, a number of parametrical studies of the μIM process were carried on an instrumented micromould and then their results were compared with the obtained numerical simulation results gathered from process modeling phenomena. Dynamical mechanical characterization of μ-moulded parts was performed in order to collect the data required for prediction of their long-term mechanical performance. Finally, after calibration of polymer material model, a long-term transient structural analysis was carried out. It was found out that the structural performance of microparts was significantly affected by the thermo-mechanical (residual) stresses. The latter is an inherent feature of the injection moulding processing, and therefore has to be accounted for the prediction of the u-moulded parts’ service life.
27
Zhang, Bo. "Magnetic fields near microstructured surfaces : application to atom chips." Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2009/2898/.
Повний текст джерелаАнотація:
Microfabricated solid-state surfaces, also called atom chip', have become a well-established technique to trap and manipulate atoms. This has simplified applications in atom interferometry, quantum information processing, and studies of many-body systems. Magnetic trapping potentials with arbitrary geommetries are generated with atom chip by miniaturized current-carrying conductors integrated on a solid substrate. Atoms can be trapped and cooled to microKelvin and even nanoKelvin temperatures in such microchip trap. However, cold atoms can be significantly perturbed by the chip surface, typically held at room temperature. The magnetic field fluctuations generated by thermal currents in the chip elements may induce spin flips of atoms and result in loss, heating and decoherence. In this thesis, we extend previous work on spin flip rates induced by magnetic noise and consider the more complex geometries that are typically encountered in atom chips: layered structures and metallic wires of finite cross-section. We also discuss a few aspects of atom chips traps built with superconducting structures that have been suggested as a means to suppress magnetic field fluctuations. The thesis describes calculations of spin flip rates based on magnetic Green functions that are computed analytically and numerically. For a chip with a top metallic layer, the magnetic noise depends essentially on the thickness of that layer, as long as the layers below have a much smaller conductivity. Based on this result, scaling laws for loss rates above a thin metallic layer are derived. A good agreement with experiments is obtained in the regime where the atom-surface distance is comparable to the skin depth of metal.
Since in the experiments, metallic layers are always etched to separate wires carrying different currents, the impact of the finite lateral wire size on the magnetic noise has been taken into account. The local spectrum of the magnetic field near a metallic microstructure has been investigated numerically with the help of boundary integral equations. The magnetic noise significantly depends on polarizations above flat wires with finite lateral width, in stark contrast to an infinitely wide wire. Correlations between multiple wires are also taken into account. In the last part, superconducting atom chips are considered. Magnetic traps generated by superconducting wires in the Meissner state and the mixed state are studied analytically by a conformal mapping method and also numerically. The properties of the traps created by superconducting wires are investigated and compared to normal conducting wires: they behave qualitatively quite similar and open a route to further trap miniaturization, due to the advantage of low magnetic noise. We discuss critical currents and fields for several geometries.Mikrotechnologische Oberflächen, sogenannte Atomchips, sind eine etablierte Methode zum Speichern und Manipulieren von Atomen geworden. Das hat Anwendungen in der Atom-Interferometrie, Quanteninformationsverarbeitung und Vielteilchensystemen vereinfacht. Magnetische Fallenpotentiale mit beliebigen Geometrien werden durch Atomchips mit miniaturisierten stromführenden Leiterbahnen auf einer Festkörperunterlage realisiert. Atome können bei Temperaturen im $mu$ K oder sogar nK-Bereich in einer solchen Falle gespeichert und gekühlt werden. Allerdings können kalte Atome signifikant durch die Chip-Oberfläche gestört werden, die sich typischerweise auf Raumtemperatur befindet. Die durch thermische Ströme im Chip erzeugten magnetischen Feldfluktuationen können Spin-Flips der Atome induzieren und Verlust, Erwärmung und Dekohärenz zur Folge haben. In dieser Dissertation erweitern wir frühere Arbeiten über durch magnetisches Rauschen induzierte Spin-Flip-Ratenund betrachten kompliziertere Geometrien, wie sie typischerweise auf einem Atom-Chip anzutreffen sind: Geschichtete Strukturen und metallische Leitungen mit endlichem Querschnitt. Wir diskutieren auch einige Aspekte von Aomchips aus Supraleitenden Strukturen die als Mittel zur Unterdrückung magnetischer Feldfluktuationen vorgeschlagen wurden. Die Arbeit beschreibt analytische und numerische Rechnungen von Spin-Flip Raten auf Grundlage magnetischer Greensfunktionen. Für einen Chip mit einem metallischen Top-Layer hängt das magnetische Rauschen hauptsächlich von der Dicke des Layers ab, solange die unteren Layer eine deutlich kleinere Leitfähigkeit haben. Auf Grundlage dieses Ergebnisses werden Skalengesetze für Verlustraten über einem dünnen metallischen Leiter hergeleitet. Eine gute Übereinstimmung mit Experimenten wird in dem Bereich erreicht, wo der Abstand zwischen Atom und Oberfläche in der Größenordnung der Eindringtiefe des Metalls ist. Da in Experimenten metallische Layer immer geätzt werden, um verschiedene stromleitende Bahnen vonenander zu trennen, wurde der Einfluß eines endlichen Querschnittsauf das magnetische Rauschen berücksichtigt. Das lokale Spektrum des magnetischen Feldes in der Nähe einer metallischen Mikrostruktur wurde mit Hilfe von Randintegralen numerisch untersucht. Das magnetische Rauschen hängt signifikant von der Polarisierung über flachen Leiterbahnen mit endlichem Querschnitt ab, im Unterschied zu einem unendlich breiten Leiter. Es wurden auch Korrelationen zwischen mehreren Leitern berücksichtigt. Im letzten Teil werden supraleitende Atomchips betrachtet. Magnetische Fallen, die von supraleitenden Bahnen im Meissner Zustand und im gemischten Zustand sind werden analytisch durch die Methode der konformen Abbildung und numerisch untersucht. Die Eigenschaften der durch supraleitende Bahnen erzeugten Fallen werden erforscht und mit normal leitenden verglichen: Sie verhalten sich qualitativ sehr ähnlich und öffnen einen Weg zur weiteren Miniaturisierung von Fallen, wegen dem Vorteil von geringem magnetischem Rauschen. Wir diskutieren kritische Ströme und Felder für einige Geometrien.
28
Anders, Sebastian [Verfasser]. "Interactions between biosystems and 3D microstructured surfaces / Sebastian Anders." München : Verlag Dr. Hut, 2019. http://d-nb.info/1181514142/34.
Повний текст джерела
29
Yeung, Chun L. "Design and fabrication of microstructured and switchable biological surfaces." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1712/.
Повний текст джерелаАнотація:
The research presented in this thesis explores the design and fabrication of microstructured and switchable biological surfaces, which may have potential applications of nanobiotechnology. The thesis focuses on the fabrication of biological surfaces which can be controlled via external stimuli. Chapter 1 - Introduction to Nanobiotechnology - presents an introduction to the background of this research including the role of self-assembled monolayers (SAMs) in nanobiotechnology, microstructure fabrication techniques, stimuli responsive surfaces and cell migration. Chapter 2 - Surface characterization techniques - presents surface characterization techniques employed throughout this research. Chapter 3 - Study of Arp2/3 complex activity in filopodia of spreading cells using patterned biological surfaces - presents the fabrication and characterization of patterned biological (fibronectin) surfaces using patterning technology (microcontact printing) and several surface analytical techniques. This study explores the role of filopodia in the spreading of Mouse Embryonic fibroblast (MEF) cells and the function of Arp2/3 complex in this process. The results demonstrated that filopodia, produced by MEF cells interacted with the patterned fibronectin surface and guided lamellipodia protrusion. Arp2/3 complex, which is absent on the filopodia adhesion site, does not facilitate in the adhesion of filopodia on the fibronectin surface. Chapter 4 - Tuning specific biomolecular interactions using electro-switchable oligopeptide surfaces - presents the fabrication of responsive surfaces that rely on electro-switchable peptides to control biomolecular interactions on gold surfaces. This system is based upon the conformational switching of positively charged oligolysine peptides that are tethered to a gold surface. The bioactive molecular moieties (biotin) terminates on the oligolysines can be reversibly exposed (bio-active state) or concealed (bio-inactive state) on demand, as a function of surface potential. Chapter 5 - Experimental procedures, protocols and synthesis - describes the experimental techniques used during the investigations performed throughout the work described in this thesis. Experimental protocols and data analysis by various equipment are described.
30
Farias, Edgardo. "Probing the liquid-vapor interface in microstructured heat exchangers." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98961.
Повний текст джерелаАнотація:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 51-52).
This thesis describes two aspects of a project designed to understand the liquid-vapor interface in microstructured heat exchangers. The two aspects include: design and fabrication of a custom vacuum chamber faceplate and the investigation of the liquid meniscus shape on microstructured devices. The faceplate for the vacuum chamber consisted of two metal components that serve to house and seal a viewport. Addition of the viewport to the chamber was of interest so that experimentation within a pure environment could be conducted.The second component of this project was to map the meniscus profile of water on three different device geometries under various conditions by laser interferometry. The first experiment was a transient study where a droplet of water fully evaporated from the surface. The purpose was to determine how the profile changes as evaporation progresses. As evaporation occurs a more curved meniscus is established within the liquid which causes a greater capillary pressure. The second experiment was a steady state study with the samples partially submerged in water. This aimed to determine the profile that arises when evaporation is balanced by fluid replenishment. The profile that arises after the first several microstructure unit cells remains constant for the remainder of the microstructured region of the sample and the meniscus has the highest curvature near the fluid front, indicating a higher capillary pressure. The final experiment was varying heat applied to the surface. The aim was to determine how the applied heat flux changes the steady state profile. With higher temperature more fluid evaporates from the surface, resulting in an increase of meniscus curvature with increased temperature.
by Edgardo Farias.
S.B.
31
Ruleman, Karlen E. (Karlen Elizabeth). "Heat transfer via dropwise condensation on hydrophobic microstructured surfaces." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54510.
Повний текст джерелаАнотація:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 22).
Dropwise condensation has the potential to greatly increase heat transfer rates. Heat transfer coefficients by dropwise condensation and film condensation on microstructured silicon chips were compared. Heat transfer coefficients are found to be seventy percent higher in the hydrophobic, dropwise condensation case relative to the hydrophilic, film condensation case. With this increased heat transfer coefficient, dropwise condensation using microstructures could improve many heat exchange applications, particularly electronics cooling.
by Karlen E. Ruleman.
S.B.
32
Xie, Enyuan. "High performance microstructured light emitting diodes : mechanisms and processes." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=18972.
Повний текст джерелаАнотація:
The research work presented in this thesis focuses on the mechanisms and development of novel III-nitride microstructured light emitting diodes (LEDs). In particular, we focus on micro-sized LEDs ('μ-LEDs') and LEDs containing micro-scale emission images i.e. 'microstructured-image LEDs'. III-nitride μ-LEDs, which are devices with dimensions less than 100μm, show improved device performance and novel potential applications compared with broad- area LEDs. The internal electric field in III-nitride materials, which is mainly caused by the strain due to lattice mismatch with the substrate, is a serious issue for III-nitride LEDs. As the strain can be relaxed in micro-scale structures, the performance of μ-LEDs can be improved. In this work, we have investigated the strain relaxation process in III-nitride micro-pillars as a function of pillar diameter by high-spatial-resolution cathodoluminescence. The results of this study give a guideline for furthe r design of μ-LEDs with high efficiency. The internal electric field can also be screened by injection of carriers, leading to a blue-shift of the emission wavelength for III-nitride LEDs. Due to the high operating current density that μ-LEDs can sustain, the magnitude of this blue-shift is remarkably increased for μ-LEDs. Based on this characteristic, colour-tunable μ-LEDs have been demonstrated in this work, which offers a simple way to achieve multi-colour displays. In order to further improve the performance of μ-LEDs, we have also developed Pd-based contacts to p-type GaN and investigated the current-density dependent specific contact resistivity. At high current densities, the μ-LEDs with optimized Pd-based contacts have better electrical performance compared with devices using oxidized Ni/Au contacts. The optimized Pd-based contact also leads to improved optical power for blue LEDs in flip-chip configurations. III-nitride microstructured-image LEDs are devices in which micro-scale emission patterns are created in single LEDs. These devices offer a simple approach to the display of high-resolution images. CHF3 plasma treatment is a novel technique used for the fabrication of these devices. This plasma treatment can locally modify the electrical properties of p-type GaN and define the emission image. An application of these devices for maskless image writing is demonstrated.
33
Shand, Matthew. "Microstructured Optical Arrays for use with soft X-rays." Thesis, King's College London (University of London), 2012. https://kclpure.kcl.ac.uk/portal/en/theses/microstructured-optical-arrays-for-use-with-soft-xrays(14a67e6f-2564-4c1d-afd5-96d5e748892b).html.
Повний текст джерелаАнотація:
Zone plates are commonly used in soft X-ray microscopy due to the high spatial resolutions achievable, however the performance is somewhat limited due to their small numerical aperture, combined with chromatic aberration and the multiple diffraction orders that are produced. Microstructured Optical Arrays (MOAs) have been proposed as an alternative method of focusing soft X-rays, using grazing incidence reflections from an array of channels, with the cumulative effect producing a small focused spot. The development and focusing properties of MOAs are described and simulated within this thesis, with comparison made to zone plates and other methods of focusing X-rays. -- Experimental characterisation of MOAs and zone plates was achieved using a microfocused electron bombardment X-ray source. Necessary developments required to examine MOAs using the X-ray source and detector system are described, along with current calibration measurements, providing insight into the overall performance of the source. -- The use of a CCD detector with the microfocus source has allowed comparison to be made between experimental measurements made to characterise the optical performance of MOAs and computer simulation.
34
Bellinger, Steven Lawrence. "Advanced microstructured semiconductor neutron detectors: design, fabrication, and performance." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/14868.
Повний текст джерелаАнотація:
Doctor of PhilosophyDepartment of Mechanical and Nuclear Engineering
Douglas S. McGregor
The microstructured semiconductor neutron detector (MSND) was investigated and previous designs were improved and optimized. In the present work, fabrication techniques have been refined and improved to produce three-dimensional microstructured semiconductor neutron detectors with reduced leakage current, reduced capacitance, highly anisotropic deep etched trenches, and increased signal-to-noise ratios. As a result of these improvements, new MSND detection systems function with better gamma-ray discrimination and are easier to fabricate than previous designs. In addition to the microstructured diode fabrication improvement, a superior batch processing backfill-method for 6LiF neutron reactive material, resulting in a nearly-solid backfill, was developed. This method incorporates a LiF nano-sizing process and a centrifugal batch process for backfilling the nanoparticle LiF material. To better transition the MSND detector to commercialization, the fabrication process was studied and enhanced to better facilitate low cost and batch process MSND production. The research and development of the MSND technology described in this work includes fabrication of variant microstructured diode designs, which have been simulated through MSND physics models to predict performance and neutron detection efficiency, and testing the operational performance of these designs in regards to neutron detection efficiency, gamma-ray rejection, and silicon fabrication methodology. The highest thermal-neutron detection efficiency reported to date for a solid-state semiconductor detector is presented in this work. MSNDs show excellent neutron to gamma-ray (n/γ) rejection ratios, which are on the order of 106, without significant loss in thermal-neutron detection efficiency. Individually, the MSND is intrinsically highly sensitive to thermal neutrons, but not extrinsically sensitive because of their small size. To improve upon this, individual MSNDs were tiled together into a 6x6-element array on a single silicon chip. Individual elements of the array were tested for thermal-neutron detection efficiency and for the n/γ reject ratio. Overall, because of the inadequacies and costs of other neutron detection systems, the MSND is the premier technology for many neutron detection applications.
35
Arvas, Serhend. "A method of moments analysis of microstructured optical fibers." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2009. http://wwwlib.umi.com/cr/syr/main.
Повний текст джерела
36
Caillaud, Céline. "Élaborations et caractérisations de fibres optiques microstructurées en verres de chalcogénures pour le moyen infrarouge." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S062/document.
Повний текст джерелаАнотація:
Les verres de chalcogénures combinent plusieurs propriétés : une transparence étendue dans l’infrarouge, un indice de réfraction élevé (n>2) et de fortes propriétés non-linéaires. La réalisation de fibres optiques microstructurées (FOMs) permet d’exacerber les effets non-linéaires et notamment en faisant varier les paramètres optogéométriques des fibres (d et Λ). Ainsi, des fibres à propagation monomode peuvent être obtenues ou encore des fibres dont les applications potentielles concernent l’optique active avec la génération d’effets non-linéaires. La réalisation de telles fibres passent par la synthèse de verres de chalcogénures de haute pureté. Par conséquent, les bandes d’absorption limitant la transparence des fibres doivent être identifiées et limitées au maximum. Pour cela, le suivi et la qualification des éléments utilisés lors de la synthèse des verres doivent être entrepris. Un protocole de synthèse et de purification par traitements thermiques a été mis en place en ce sens. La technique pour élaborer les FOMs en verres de chalcogénures est le moulage. Elle consiste à couler un verre dans un moule entièrement réalisé en silice. Ce dernier présente la géométrie inverse de la fibre désirée. Cette méthode permet d’obtenir des géométries variées et reproductibles en passant par des fibres monomodes et multimodes avec des diamètres de cœur allant de 2 μm jusqu’à plus de 20 μm. La réalisation de sources infrarouges a été développée dans le manuscrit. Cela a été rendu possible dans un premier temps par la génération d’un supercontinuum à l’aide d’une fibre à cœur suspendu puis par la réalisation d’un laser à cascade quantique (QCL) couplé à une fibre monomode. De plus, une fibre à maintien de la polarisation (FMP) dans le moyen infrarouge, présentant une biréfringence de groupe de l’ordre de 10-3 a été élaborée grâce à l’évolution du moule de silice. De plus, un coupleur tout-optique, une fibre toute-solide et un faisceau de fibres infrarouges complètent les réalisations obtenues au cours de cette thèseChalcogenide glasses combine several properties : large transparency in the infrared range, a high refractive index (n>2) and strong non-linear properties. The realization of microstructured optical fibers (MOFs) exacerbates non-linear effects more particularly by varying the opto-geometrical parameters of the fibers (d and Λ). Thus, single-mode propagation can be obtained and also generation of non-linear effects. The realization of high purity chalcogenide glasses is needed. In fact, absorption bands limiting the transparency of the fibers must be identified and minimized. For this, monitoring and qualification of components used in the synthesis of glasses should be undertaken. A protocol of synthesis and purification by heat treatment was implemented in this direction. The technique to elaborate MOFs is the casting method. It consists of flowing a glass on a silica mold. The geometry is the negative shape of the desired fiber. This method allows the realization of multimode or single-mode fiber in the 1-10 μm window. The realization of infrared sources was developed in the manuscript. The generation of a supercontinuum with a suspended-core fiber has been presented and also by the realization of a quantum cascade laser (QCL) coupled into a singlemode fiber. In addition, a polarization-maintaining fiber (PMF) having a group birefringence of the order of 10-3 was developed through the evolution of the silica mold. In addition, an optical coupler, an all-solid fiber and an infrared bundle were achieved during this thesis
37
Sudirman, Azizahalhakim. "Combining Reflectometry, Ablation and Fluid Collection in a Microstructured Fiber." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-20818.
Повний текст джерелаАнотація:
The purpose of the diploma work is to investigate the possibilities to combine three different areas; reflectometry, microfluidics and laser ablation in a microstructured single-mode fiber, thus obtaining a controlled technique for positioning for ablation and collection of liquids from small inclusions.
Each of the three areas is thoroughly described in different sections of this report. The first part of the experiments in this diploma work consisted of combining reflectometry and microfluidics, the second part combining reflectometry with laser ablation and the final experiment setup consisted of a combination of all three areas. An artificial system for liquid collection was then designed for that purpose.
The results obtained from experiments and measurements clearly demonstrate that combining reflectometry, laser ablation and fluid collection in a single optical fiber is promising. Future work will include improvements of the technique towards a medical application for bone marrow transplantation.
38
Olaru, Maria Alexandra [Verfasser]. "Dynamic NMR of nano- and microstructured materials / Maria Alexandra Olaru." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1046633023/34.
Повний текст джерела
39
Marel, Anna-Kristina. "Quantitative studies of collective cell migration using novel microstructured molds." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-182401.
Повний текст джерела
40
Jovanovic, Natalija Zorana. "Microstructured tungsten thermophotovoltaic selective emitters c by Natalija (Zorana) Jovanović." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44445.
Повний текст джерелаАнотація:
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 71-74).
This research investigates the fabrication, modeling, characterization, and application of tungsten two-dimensional (2D) photonic crystal (PhC) structures as selective emitters and means of achieving higher efficiencies in thermophotovoltaic (TPV) energy conversion systems. Important aspects of the fabrication process are researched, developed, and rigorously characterized, focusing on dimensional reliability, precision, and repeatability of the processes. A major contribution in the form of tungsten reactive ion etch (RIE) characterization is provided with detailed parameters and second-order influences on etch rate, smoothness, and mask erosion. Optical characterization of our prototypes is found to be in excellent agreement with simulation, and has provided an experimental confirmation of selective emitter performance. We show that selective emitters can substantially increase spectral efficiency, providing as much as three times the radiative power density of planar tungsten. We include the first measurement of 96% combined efficiency of a selective emitter and a dielectric stack mirror for TPV system applications.
Sc.D.
41
Zhu, Yangying. "Magnetic tunable microstructured surfaces for thermal management and microfluidic applications." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82355.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 46-47).
Micro and nanostructured surfaces have broad applications including heat transfer enhancement in phase-change systems and liquid manipulation in microfluidic devices. While significant efforts have focused on fabricating static micro/nanostructured arrays, uniform arrays that can be dynamically tuned have not yet been demonstrated. In this work, we present a novel fabrication process for magnetically tunable microstructured surfaces, where the tilt angle can be controlled upon application of an external magnetic field. We also demonstrated this platform for droplet manipulation in heat transfer applications. The tunable surfaces consist of ferromagnetic nickel (Ni) pillars on a soft PDMS substrate. The pillars have diameters of 23-35 [mu]m, pitches of 60-70 [mu]m, and heights of 70-80 [mi]m. We used vibrating sample magnetometry to obtain hysteresis loops of the Ni pillar arrays which match well the properties of bulk Ni. With a field strength of 0.5 tesla and a field angle of 600, a uniform 10.5± 1 tilt angle of the pillar arrays was observed. Furthermore, we developed a model to capture the tilt angle as a function of the magnetic field, and showed that by replacing nickel to cobalt, the tilt angle could be increased to 30' with the same field. Meanwhile, simulations show good agreement with the experiments. Future work will focus on using these surfaces to actively transport water droplets and spread the liquid film via pillar movement. This work promises tunable surface designs for important device platforms in microfluidics, biological and optical applications.
by Yangying Zhu.
S.M.
42
Shao, N. "Gas-liquid two-phase flow and reaction in microstructured reactors." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19893/.
Повний текст джерелаАнотація:
The thesis presents investigations on two-phase gas-liquid microstructured reactors operating in Taylor flow and the dependence of reactor performance on design parameters. Literature review revealed that flow patterns in microchannels are affected not only by channel dimension, fluids flowrates and surface tension, but also by wall wettability and gas inlet size. A universal flow regime map does not seem to exist. The hydrodynamic parameters of Taylor flow were investigated both by Computational Fluid Dynamics simulations and experiments in microstructures with sizes 0.3mm – 1mm and various inlet configurations such as T- and Y- junctions fabricated in-house. The same parameters that influence flow patterns and their transitions were also found to affect Taylor bubble sizes. To account for the effect of inlet conditions, correlations were developed for predicting bubble/slug size in the T- and Y- inlet geometries that were used subsequently. Mass transfer with and without chemical reaction was investigated numerically in Taylor flow microreactors using CO2 physical absorption into water or chemical absorption into NaOH aqueous solution. Chemical absorption was enhanced by a factor of 3-18 over physical absorption. With reaction present, the reactor performance depended mainly on the gas-liquid interfacial area, while mixing within the phases was only important in physical absorption. This agreed with the experimental results of a similar reaction system, which showed that bifurcating main channels, where new interfaces are generated, significantly improved reaction conversion while meandering channels that enhance liquid mixing had little impact. Finally, the performance of a Taylor flow microreactor was evaluated for an industrial fast gas-liquid reaction of CO2 absorption from fuel gas into amine solutions. The Taylor flow microreactor offered the largest specific area and the smallest reactor volume compared to other microreactor types. However, in order to meet absorption specifications for the case considered multistage absorption would have been necessary.
43
Asimakis, Symeon. "Nonlinear applications of step-index and microstructured soft-glass fibres." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/65526/.
Повний текст джерелаАнотація:
This thesis focuses on the potential of compound-glass, highly nonlinear, small-core fibres for use in nonlinear applications. Both fibres with a conventional step-index design and small-core holey fibres are considered. While the former technology is more mature, the latter represents the ultimate candidate, since it offers the flexibility of combining novel dispersion properties with a very high nonlinearity. With regard to holey fibre designs, small-core, compound-glass holey fibres with different core diameters and designs are considered for two different background materials: a commercially available lead-silicate glass and a bismuth-oxide based glass. Firstly, characterization measurements are performed on the fabricated holey fibres. The measurements reveal the advantages of each glass type and each fibre design, the ultra-high nonlinearity that can be achieved in such fibres and the potential of achieving simultaneously a novel dispersion profile and high nonlinearity. Nonlinear applications are then demonstrated for some of the fibres presented. In particular, the use of a lead-silicate holey fibre, having a dispersion-shifted profile, with a zero-dispersion wavelength lying close to the C-band is demonstrated in cross-phase modulation based wavelength conversion and switching applications in the 1.55 μm window. Both a co-polarized pump and probe scheme and a Kerr-shutter configuration are considered. For the same fibre, the stimulated four-wave mixing process for amplification and wavelength conversion applications in the C-band is thoroughly studied. Numerical simulations and experimental findings are combined to study the fibre performance, demonstrate its applicability to nonlinear wavelength conversion applications and identify future improvement objectives. The suitability of compound-glass holey fibres is also examined for the generation of correlated photons, through spontaneous four-wave mixing, and the generation of a broad supercontinuum by pumping at the convenient in terms of high power laser availability wavelength regions of 1.0 μm and 1.5 μm. The experiments presented in this thesis constitute the first nonlinear applications ever reported for dispersion-tailored, compound-glass holey fibres, clearly revealing their potential in fibre-based nonlinear applications. Nonlinear applications are also demonstrated for a commercially available, fiberised, bismuth-oxide based fibre with a step-index design. Using this fibre, an all-optical regenerator of Return-to-Zero picosecond pulses is realized at repetition rates of 10 and 40 Gb/s. The same fibre is also employed in an all-fiberised pulse compression scheme, which relies on nonlinear pulse propagation in the normal dispersion regime and enables the compression of picosecond pulses down to the femtosecond scale. In both applications, the ultra high nonlinearity of the compound-glass, step-index fibre results in reduced fibre-length and peak power requirements. The thesis concludes by addressing the issues concerning the practicality of compound-glass fibres and proposing potential future directions.
44
Tse, Ming-Leung Vincent. "Development and applications of dispersion controlled high nonlinearity microstructured fibres." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/50200/.
Повний текст джерелаАнотація:
In this thesis I investigate aspects of dispersion controlled high nonlinearity all silica holey fibre, including design, fabrication, sample applications, and modelling. The latest work has been focussed on controlled structural variation of holey fibres along their length to obtain fibre with a longitudinal variation of dispersion and nonlinearity. I fabricated a dispersion-decreasing holey fibre and performed the first demonstration of soliton compression in a holey fibre. A compression factor of 2 has been achieved with pJ pulses at 1.06 μm. Further numerical modelling has been carried out from a holey fibre design contour map, to optimize holey fibre tapers for soliton compression at 1.55 μm. A compression factor of 6 is possible in a 15-m holey fibre taper with a loss of 0.1 dB/m.
45
Amezcua-Correa, Adrian. "Deposition of electronic and plasmonic materials inside microstructured optical fibres." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/50201/.
Повний текст джерелаАнотація:
Optical fibres are the transport medium of today's digital information. Nowadays, modern optical telecommunication systems make use of semiconductor optoelectronic devices to generate, control and detect light. The union of the two technologies, namely fibre photonics and semiconductor electronics is expected to have a major impact on next generation of optoelectronic devices, exploiting both the guiding capabilities of optical fibres and the signal processing properties of semiconductors devices. Only recently, with the advent of microstructured optical fibres and templating material processing methods, it has been possible to create optical fibres with solid-state material inclusions. An experimental investigation on the optical transmission properties of microstructured optical fibres impregnated with silver nanoparticles is also presented. These fibres are shown to be an excellent way of coupling optical guided modes into surface plasmons. As a result, they represent a promising platform technology for fully integrated photonic/plasmonic devices. These fibres have demonstrated the enhancement of Raman signals from molecules adsorbed onto the inner metal surfaces and thus ideally suited for Surface Enhance Raman Scattering molecular detection.
46
Mart, Cody, Benjamin Pulford, Benjamin Ward, Iyad Dajani, Thomas Ehrenreich, Brian Anderson, Khanh Kieu, and Tony Sanchez. "Power scaling of a hybrid microstructured Yb-doped fiber amplifier." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/625057.
Повний текст джерелаАнотація:
Hybrid microstructured fibers, utilizing both air holes and high index cladding structures, provide important advantages over conventional fiber including robust fundamental mode operation with large core diameters (>30 mu m) and spectral filtering (i.e. amplified spontaneous emission and Raman suppression). This work investigates the capabilities of a hybrid fiber designed to suppress stimulated Brillouin scattering (SBS) and modal instability (MI) by characterizing these effects in a counter-pumped amplifier configuration as well as interrogating SBS using a pump-probe Brillouin gain spectrum (BGS) diagnostic suite. The fiber has a 35 mu m annularly gain tailored core, the center doped with Yb and the second annulus comprised of un-doped fused silica, designed to optimize gain in the fundamental mode while limiting gain to higher order modes. A narrow-linewidth seed was amplified to an MI-limited 820 W, with near-diffraction-limited beam quality, an effective linewidth similar to 1 GHz, and a pump conversion efficiency of 78%. Via a BGS pump-probe measurement system a high resolution spectra and corresponding gain coefficient were obtained. The primary gain peak, corresponding to the Yb doped region of the core, occurred at 15.9 GHz and had a gain coefficient of 1.92x10(-11) m/W. A much weaker BGS response, due to the pure silica annulus, occurred at 16.3 GHz. This result demonstrates the feasibility of power scaling hybrid microstructured fiber amplifiers
47
Loewenberg, Michael Gavalas George R. "A theoretical study of reaction and diffusion in microstructured materials /." Diss., Pasadena, Calif. : California Institute of Technology, 1988. http://resolver.caltech.edu/CaltechETD:etd-06142006-135258.
Повний текст джерела
48
Kuhlmey, Boris T. "Theoretical and Numerical Investigation of the Physics of Microstructured Optical Fibres." University of Sydney and Universite Aix-Marseille III. School of Physics, 2003. http://hdl.handle.net/2123/560.
Повний текст джерелаАнотація:
We describe the theory and implementation of a multipole method for calculating the modes of microstructured optical fibers (MOFs). We develop tools for exploiting results obtained through the multipole method, including a discrete Bloch transform. Using the multipole method, we study in detail the physical nature of solid core MOF modes, and establish a distinction between localized defect modes and extended modes. Defect modes, including the fundamental mode, can undergo a localization transition we identify with the mode�s cutoff. We study numerically and theoretically the cutoff of the fundamental and the second mode extensively, and establish a cutoff diagram enabling us to predict with accuracy MOF properties, even for exotic MOF geometries. We study MOF dispersion and loss properties and develop unconventional MOF designs with low losses and ultra-flattened near-zero dispersion on a wide wavelength range. Using the cutoff-diagram we explain properties of these MOF designs.
49
Kuhlmey, Boris T. "Theoretical and numerical investigation of the physics of microstructured optical fibres." Connect to full text, 2004. http://setis.library.usyd.edu.au/adt/public_html/adt-NU/public/adt-NU20040715.171105.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--School of Physics, Faculty of Science, University of Sydney, 2004. (In conjunction with: Université de Droit, d'Économie et des Sciences d'Aix-Marseille (Aix Marseille III)).Bibliography: leaves 196-204.
50
Zhang, Yun Hua. "Analysis and design of microstructured fibres for optical and terahertz applications." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539676.
Повний текст джерела