Tesi sul tema "Pulsed laser treatment"

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O objetivo desse estudo in vivo foi verificar a resposta óssea de scaffolds porosos revestidos processados pela técnica de Sinterização Direta de Metais a laser (DMLS) associado à terapia de ultrassom de baixa intensidade. Os scaffolds foram processados empregando a técnica DMLS e tratados termicamente a 1000°C por 24 horas. Três tipos de tratamento de superfície foram avaliados: Alcalino, biomimético e imobilização de alendronato de sódio. Para o tratamento alcalino, as amostras foram imersas na solução de NaOH (5M) a 60ºC por 24 horas. O tratamento biomimético consistiu na imersão dos scaffolds em solução SBF (SimulatedBodyFluid) enquanto a imobilização do alendronato foi realizada a partir da imersão dos scaffolds em uma solução formada por SBF e medicamento durante 5 dias. As superfícies dos scaffolds foram avaliadas para cada etapa empregando microscopia eletrônica de varredura (MEV) e análise por difração de raios-X. Os scaffolds foram implantados na tíbia direita de 85 ratos machos da raça wistar com idade média de 12 semanas. A microtomografia computadorizada (µCT) e análise histológica foram realizadas para avaliar o reparo ósseo no defeito. As micrografias das superfícies obtidas mostraram mudanças no aspecto da superfície e composição química de acordo com o tratamento. O tratamento biomimético promoveu o crescimento da apatita sobre a superfície enquanto a imobilização com alendronato suprimiu sua formação. As imagens obtidas na microtomografia mostraram elevado valor de densidade óssea para o último grupo. No entanto, análises histológicas mostraram a formação de cápsula fibrosa em torno dos scaffolds a qual foi minimizada usando ultrassom pulsado de baixa intensidade. No entanto, mais estudos precisam ser realizados para avaliar a influência da geometria dos scaffolds na incorporação de medicamentos.
The objective of this in vivo study was to verify the bone response of coated Ti6Al4V porous scaffolds processed by Direct Metal Laser Sintering (DMLS) technique associated to low intensity pulsed ultrasound therapy. Scaffolds were processed by using Direct Metal Laser Sintering technique (DMLS) and heat treated at 1000 °C for 24 hours. Three types of surface treatments were evaluated: alkaline, biomimetic and sodium alendronate immobilization. For alkaline treatment, samples were immersed in a NaOH (5M) solution at 60ºC for 24 hours. Biomimetic treatment consisted in the immersion of the scaffolds into Simulated Body Fluid solution while for sodium alendronato immobilization the scaffolds were immersed in the solution formed by SBF plus drug during 5 days. The scaffolds surfaces were evaluated after each step employing SEM (Scanning Electron Microscopy)and X-rays diffraction analysis(XRD). Scaffolds were implanted into right tibia of 85 male Wistar rats with average age of 12 weeks. X-rays micro-computed tomography (µCT) and histological analysis were carried out to evaluate the bone repair on the defect. Micrographs analysis showed that the aspect of the surfaces and chemical composition changed according treatment. Biomimetic treatment promoted the growth of the apatite on the surface; in contrast the immobilization of alendronate suppressed apatite formation. Micro CT images showed higher value of bone density for the last group. However, histological analysis showed the formation of encapsulation fibrous around the scaffolds. This formation was minimized by using low intensity pulsed ultrasound technique, however, more studies can be carried out to evaluate the influence of scaffolds geometry in the drug incorporation.

Les matériaux ferromagnétiques doux, souvent employés sous la forme de tôles laminées fines, sont utilisés dans les stators et rotors des machines électriques tournantes. Le rendement de ces machines est réduit par des pertes dites "pertes fer", dues aux mécanismes d'aimantation et aux courants induits. La nature du matériau reflétée par sa structure magnétique couplée à la géométrie, à l'anisotropie et à la texture de la surface sont autant de facteurs qui influent sur les performances électromagnétiques finales. Ces travaux de thèse ont donc pour objectif de proposer des matériaux magnétiques sur mesure par texturisation laser sélective de surface pour des dispositifs électromagnétiques tels que les machines électriques tournantes. L'applicabilité d'un tel procédé au niveau industriel pour des matériaux à grains orientés ou à grains non orientés dans les machines électriques nécessite de contrôler davantage la technologie et les spécifications du procédé dans le but d'optimiser les propriétés électromagnétiques. En effet, l'impact déterministe de cette technique sur la structure magnétique d'un matériau et ses performances observables (perméabilité magnétique et pertes fer) reste incomplètement appréhendé, modélisé et connu. Les conditions d'industrialisation doivent être analysée et optimisée vis-à-vis des contraintes techniques et économiques. On cherche donc ici à étudier l'impact d'une texturisation de surface par laser pulsé sur la structure magnétique en surface et en volume d'un matériau pour pouvoir les contrôler. L'adaptation des procédés laser avec augmentation de la vitesse de traitement est étudiée théoriquement, puis engagée et vérifiée expérimentalement pour correspondre aux ambitions d'industrialisation. Ainsi, ce travail effectué en très grande proximité avec le projet européen H2020 ESSIAL permettra de proposer différents traitements de surface adaptés aux machines tournantes pour ajuster certaines propriétés magnétiques, de façon théorique et expérimentale
Soft ferromagnetic materials, which are often used in the form of laminated sheets, compose rotating electrical machines' stators and rotors. The efficiency of those machines is reduced by losses called "iron losses", induced by magnetization mechanisms and eddy currents. Those magnetization reversal mechanisms can only be explained with the magnetic structure coupled to the material geometry, anisotropy and surface texture, which are also deterministic factors for the final electromagnetic performances. Then, present work aims at proposing tailor-made soft ferromagnetic materials by means of selective laser texturizing for electromagnetic devices such as rotating electrical machines. To apply such a process at an industrial level for grain-oriented and non-grain-oriented materials in electrical machines, it is necessary to better control the associated technology and specify the process in order to optimize electromagnetic properties. Indeed, the deterministic impact of this technic on a material's magnetic structure and its performances (magnetic permeability and iron losses) remains partially modelled and understood. The integration of such solution at the industrial scale must be analyzed and optimized regarding technical and economical constraints. In this work, the study of the impact of laser surface texturizing on magnetic structure (regarding surface and volume) of a material with the aim to control it is performed. Future industrialization requires to adapt the pulsed laser processes at a higher speed which has been theoretically studied, initiated and experimentally verified. To finish, present work performed in parallel with the H2020 European project ESSIAL will allow to propose different surface treatments adapted to rotating machines to adjust some quantifiable electromagnetic properties with the help of both experimental and theoretical tools

Les matériaux métalliques sont utilisés dans des conditions de plus en plus sévères et doivent présenter une parfaite intégrité sur des périodes de plus en plus longues. L'objectif de ce travail de thèse est d'évaluer le potentiel d'un traitement de refusion laser pour améliorer la résistance à la corrosion d'un acier inoxydable de type 304L ; l'utilisation du laser dans le domaine des traitements de surface constituant un procédé en pleine évolution à cause des changements récents dans la technologie des lasers. Dans le cadre de ce travail, le choix du laser s'est porté sur un laser nano-impulsionnel à fibre dopée ytterbium dont les caractéristiques permettent la fusion quasi-instantanée sur quelques microns de la surface traitée, immédiatement suivie d'une solidification ultra-rapide avec des vitesses de refroidissement pouvant atteindre 1011 K/s. La combinaison de ces processus favorise l'élimination des défauts surfaciques, la formation de phases hors équilibre, la ségrégation d'éléments chimiques et la formation d'une nouvelle couche d'oxyde dont les propriétés sont gouvernées par les paramètres laser. Afin de les corréler avec la réactivité électrochimique de la surface, l'influence de deux paramètres laser sur les propriétés physico-chimiques de la surface a été étudiée : la puissance du laser et le taux de recouvrement des impacts laser. Pour clarifier ces relations, la résistance à la corrosion par piqûration des surfaces traitées a été déterminée par des tests électrochimiques. Pour des paramètres laser spécifiques, le potentiel de piqûration d'un acier inoxydable de type 304L augmente de plus de 500 mV traduisant ainsi une meilleure tenue à la corrosion localisée en milieu chloruré. L'interdépendance des différents phénomènes résultant du traitement laser a rendu complexe la hiérarchisation de leur effet sur la sensibilité de l'alliage testé. Cependant, il a été montré que la nature de l'oxyde thermique formé au cours de la refusion laser et ses défauts sont du premier ordre pour l'amorçage des piqûres.

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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

La technologie laser pulsé est l'une des solutions d'optimisation des propriétés électromagnétiques de certains aciers électriques. Cependant, son application industrielle pour différents alliages, différentes épaisseurs ou applications reste limitée. Par ailleurs, l'impact déterministe de cette technique sur la structure magnétique d'un matériau et sur ses performances nécessite des recherches approfondies. De plus, la technique d'ablation laser à impulsions ultra-courtes reste méconnue pour les aciers électriques. Elle représente cependant un potentiel important en terme de procédé reproductible et résilient aux élévations de température. L'objectif général de la thèse est d'étudier l'influence des traitements de surface par laser impulsionnel sur les propriétés magnétiques des aciers électriques de type Fer Silicium à Grains-Orientés afin d'améliorer leurs performances. Il est tout d'abord proposé une classification des différents procédés laser en fonction de la durée d'impulsion, de sa fréquence de répétition, de son intensité et de sa fluence. Trois familles de procédés sont retenues : l'irradiation, la gravure ou "scribing" et l'ablation. Une attention particulière sera portée sur ce dernier. Un des critères particulièrement analysé sera l'efficacité de la conversion d'énergie (i.e. surtout les pertes fer). Pour cela, l'impact de ces procédés laser est étudié à l'aide de modèles d'aimantation dynamique et de pertes, identifiés grâce à des mesures magnétiques par un banc dédié : le banc SST "Single Sheet Tester". Une optimisation des paramètres d'ablation laser est effectuée afin d'assurer une réduction des pertes fer de l'ordre de 20% tout en préservant la perméabilité magnétique en certains points de fonctionnement (inductions moyenne et forte à 50 Hz et basse induction jusqu’à 5000 Hz). Une étude complémentaire avec deux qualités différentes (FeSi GO conventionnel 0,23 mm et FeSi GO HiB 0,28 mm) a aussi permis d'adapter les paramètres et les motifs laser avec l'épaisseur du matériau. Il est également montré que le procédé d'ablation peut résister à des élévations de température supérieures aux autres procédés tout en acceptant l'application d'un revêtement isolant. En outre, une corrélation entre les paramètres énergétiques optiques (énergie d'une impulsion, densité d'énergie cumulative et densité de puissance pic) les motifs et impacts physiques des tracés laser (profondeur de gravures, zone affectée thermiquement, contrainte thermique induite ...) et finalement les paramètres magnétiques identifiés (coefficients de Bertotti ; paramètres du modèle Lambda) est présentée. Cette étude révèle certaines interprétations physiques. De plus, l'impact des traitements laser de surface sur la structure en domaines magnétiques a été analysé en visualisant le changement des domaines magnétiques. Des images magnéto-optiques par la technique MOIF "Magneto-Optical Indicator Film") sont présentés pour une vue d'ensemble sur les domaines principaux entre les tracés laser avec une résolution de l’ordre de 20 m. Des observations plus précises avec une résolution horizontale de l'ordre de 100 nm sont réalisées à l'aide du Microscope à Force Magnétique (MFM) afin d'avoir accès aux détails de cette structure à proximité et sur les tracés laser. Pour conclure, les analyses des paramètres d'ablation laser sont effectuées en assurant une réduction des pertes fer à 50 Hz avec un taux atteignant plus de 30 % pour une induction allant jusque 0,5 T et de l'ordre de 15 % au-dessus de 1,5 T. À plus haute fréquence et à 0,1 T, le taux de réduction peut dépasser 30%. Parallèlement, la perméabilité apparente peut soit être accrue en dessous de 1,2 T (coude de saturation), soit être préservée ou légèrement réduite entre 1,2 T et la saturation. Dans tous les cas, la polarisation J800 > 1,70 T (GO conventionnel) et J800 > 1,80 T (GO HiB) pour un champ magnétique de 800 A/m sera toujours garantie même après traitement laser
Pulsed laser technology is one of the productive solutions adopted to optimize the electromagnetic properties of certain electrical steels. However, its industrial application on different alloys, thicknesses, or applications remains restricted. Moreover, the deterministic impact of this technique on the magnetic structure of a material and its performance requires deep investigation. Further, the ultra-short pulsed laser ablation technique remains unfamiliar for electrical steels although it represents a vital potential in terms of a repeatable process that withstands high temperatures. The main intention of the thesis is to study the influence of surface laser treatments on the magnetic properties of grain-oriented silicon iron electrical steels in order to improve their performance. A classification of the different laser processes is proposed according to the pulse duration, repetition frequency, power, and laser fluence. Accordingly, three types of treatments are selected: irradiation, scribing, and ablation, with a particular emphasis on the ablation process. Remarkably, the principal criterion analyzed was the energy conversion efficiency (i.e. especially iron losses). On that account, the impact of these laser processes is studied using dynamic magnetization and loss models, identified by magnetic measurements with an SST "Single Sheet Tester" bench. Then, an optimization of the laser ablation parameters is carried out to ensure a reduction in iron losses of around 20% while maintaining the apparent permeability at certain operating points (medium and high inductions at 50 Hz and low inductions up to 5000 Hz). An additional study on two different grades of FeSi GO (conventional 0.23 mm and HiB 0.28 mm) permitted the adaptation of the laser parameters and patterns with the material thickness. Spectacularly, the ablation process has shown more resistance to a higher temperature than other processes. Furthermore, a correlation between the optical energy parameters (pulse energy, cumulative energy density, and peak power density), the patterns and laser impacts (groove depth, heat affected zone, induced thermal stress), and the identified magnetic parameters (Bertotti coefficients; Lambda model parameters) is presented. This study reveals some physical interpretations.Besides, the effect of surface laser treatments on the magnetic domain structure has been analyzed. We visualized the changes in magnetic domains with Magneto-optical images using the MOIF technique (Magneto-Optical Indicator Film) for an overview of the domains between the laser lines with a resolution of about 20 µm. Following this, more precise observations with a horizontal resolution of the order of 100 nm were performed using the Magnetic Force Microscope (MFM), which shows the structural details in the vicinity and in the laser tracing line. To conclude, an optimization of the laser ablation parameters is accomplished ensuring an iron loss reduction at 50 Hz with more than 30% for an induction 0.5 T, and a percentage of 15% for an induction above 1.5 T. At higher frequencies and for 0.1 T, the reduction percentage can exceed the 30%. Concurrently, the apparent permeability can either be enhanced below 1.2 T (saturation inclination) or slightly reduced between 1.2 T and saturation. Anyhow, the polarization J800 > 1.70 T (conventional GO) and J800 > 1.80 T (GO HiB) under a magnetic field of 800 A/m will be guaranteed after laser treatment

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

La propagation d'impulsions laser ultra-courtes et ultra-intenses dans l'atmosphère est de plus en plus étudiée. Un contrôle précis de la focalisation du champ laser et de la distribution des filaments de lumière qui s’étendent au-delà du foyer est nécessaire pour de nombreuses applications, comme la mission d'exploration de Mars qui comprend l'analyse des éléments chimiques à l'aide de la spectroscopie de désintégration induite par laser (LIBS), l'analyse de la composition de l'atmosphère par des techniques de détection et de télémétrie lumineuses (LIDAR), le déclenchement et le guidage de décharges électriques entre les nuages, ou la génération de lasers à lumière blanche par filamentation laser. Un contrôle quantitatif des propriétés de l'impulsion laser est très difficile en raison de l'interaction non-linéaire complexe entre l'impulsion laser intense et le milieu. Actuellement, les méthodes couramment utilisées reposent sur le contrôle des paramètres initiaux de l’impulsion laser en fonction du champ laser observé sur la cible. La grande dimension de l'espace des paramètres et la sensibilité des résultats aux conditions initiales rendent l'ajustement du champ laser hors du laboratoire difficile et inefficace pour répondre aux exigences des applications pratiques. Dans ce contexte, cette thèse propose une réponse à quelques-uns des défis de la propagation d’impulsions laser femtoseconde à longue portée, basée sur des scénarios de modulation de l'impulsion laser qui garantissent d'atteindre un champ laser sur cible avec les propriétés souhaitées. Ces scénarios ont été obtenus en associant méthodes d'ingénierie inverse et simulations numériques. Nous montrons que différents champs cibles peuvent être facilement et efficacement atteints en modulant le champ en sortie du laser. Chaque fois que cela est possible, la modulation est obtenue par simulation de la propagation inverse du champ cible vers le laser. Cette thèse se concentre sur deux objectifs différents de contrôle du champ laser : la projection à longue distance dans l'air (1) d'un filament de longueur prédéfinie, et (2) d’une intensité élevée.(1) Pour atteindre le premier objectif, une des innovations de cette thèse consiste à introduire un faisceau intermédiaire contrôlable proche de la cible, de type Bessel-Gauss, et à utiliser un algorithme numérique pour propager ce champ électrique en avant afin d’obtenir la distribution des filaments au point cible ainsi que rétropropager le champ intermédiaire pour obtenir la sortie laser souhaitée. Les paramètres de sortie laser obtenus sont ensuite liés aux caractéristiques du filament (point de départ, longueur, densité), fournissant une carte des paramètres clés définissant l'impulsion laser modulée qui peut être projetée sur le champ cible et le filament désirés.(2) Pour l'objectif de transmission d’intensités élevées à des distances kilométriques, nous examinons la propagation non-linéaire de faisceaux d'Airy circulaires et montrons qu'une puissance laser de quelques dizaines de GW est suffisante pour ioniser l'air et former un filament court à une distance de 1 km, ce qui pourrait faciliter les conditions de fonctionnement du laser par rapport aux lasers de classe TW utilisés dans les solutions conventionnelles pour projeter des intensités élevées à ces distances.Dans une étude séparée, nous proposons une amélioration de l'algorithme d'analyse élémentaire du spectre LIBS. L’algorithme est appliqué à la détection en ligne de la teneur en KCl et H[dollar]_2[dollar]O dans les engrais potassiques par LIBS, dans lequel la modélisation de régression de corrélation des spectres LIBS est combinée à un algorithme d'apprentissage automatique qui extrait efficacement les informations liées aux changements de contenu élémentaire à partir des spectres en ligne complexes, ce qui améliore considérablement la vitesse de détection tout en garantissant la précision de la détection et renforce encore la compétitivité
The propagation of ultrashort and ultra-intense laser pulses in the atmosphere is increasingly studied.Precise control of the focusing of the laser field and the distribution of light filaments extending beyond the focus is required for many applications, such as the Mars exploration mission on the analysis of chemical elements using Laser Induced Breakdown Spectroscopy (LIBS), the analysis of the composition of air by Light Detection and Ranging (LIDAR) techniques, the triggering and guiding of electric discharges between clouds, or the generation of white light laser by filamentation. A quantitative control of the light pulse properties is very difficult due to the complex nonlinear interaction between the intense laser pulse and the medium. At present, commonly used methods rely on the parameter control of the initial laser output and the feedback of the field at the target position. The high-dimension of the parameter space and the high sensitivity of the results to the initial conditions make the adjustment of the laser field outside the laboratory difficult and inefficient to meet the requirements of practical applications.In this context, this thesis proposes an answer to some of the challenges of long-range femtosecond laser pulse propagation, based on laser pulse modulation scenarios that guarantee to reach an on-target laser field with the desired properties. These scenarios were obtained by combining reverse engineering methods and numerical simulations. We show that different target fields can be easily and efficiently achieved by modulating the laser output field. Whenever possible, the modulation is obtained by simulating the reverse propagation of the target field towards the laser.This thesis focuses on two different objectives of laser field control: the long-range projection in the air of (1) a filament of predefined length, and (2) high intensity.(1) To achieve the first objective, one of the innovations of this thesis consists in introducing a controllable intermediate Bessel-Gauss beam close to the target, and in using a numerical algorithm to propagate this electric field forward in order to obtain the distribution of the filaments at the target point as well as back-propagate the intermediate field to obtain the desired laser output. The obtained laser output parameters are then related to filament features (starting point, length, density), providing a map for the key parameters defining the modulated laser pulse that can be projected onto the desired target field and filament.(2) For the objective of transmitting high intensities at kilometric distances, we examine the nonlinear propagation of circular Airy beams and show that a laser power of a few tens of GW is sufficient to ionize the air and form a short filament at a distance of 1 km, which could facilitate laser operating conditions compared to TW-class lasers used in conventional solutions to project high intensities at these distances.In a separate study, we propose an improvement of the elemental analysis algorithm of LIBS spectrum. The algorithm is applied to the extit{in situ} online detection of KCl and H[dollar]_2[dollar]O content in potash fertilizer by LIBS, in which correlation regression modeling of LIBS spectra is combined with a machine learning algorithm that efficiently extracts the information related to elemental content changes from the complex online collected spectra, which greatly improves the detection speed while ensuring the detection accuracy and further enhances the competitiveness

碩士
國立臺灣大學
機械工程學研究所
106
In this study, the PEDOT:PSS (CLEVIOS™ HIL-E 100 from Heraeuse) films coated on glass substrate was treated by CO2 pulsed laser in the air. The property of the PEDOT:PSS was investigated by in-line four-point probe array, spectrophotometry, AFM, SEM, and XPS. Through manipulating the fluence and the scan speed of the laser, the change in PEDOT:PSS property induced by CO2 pulsed laser was analyzed. The conductivity of the film was enhanced from 2.83E-02 S/cm to 59.4 S/cm in 181 seconds as a result of the remove of the residual water. Meanwhile, the average transmittance decreased from 89.1219 % to 88.4766 %, and the RMS roughness increased from 2.27 nm to 2.49 nm. The conductivity enhancement might be caused by the reunion between PEDOT:PSS moleculars, and the rise in the surface PEDOT/PSS ratio as investigated by SEM and XPS. However, when the laser power excess the durability of PEDOT:PSS, some significant decrease in conductivity and transmittance was observed. Compared with the hotplate thermal traetment in the air, which can not significantly increase the conductivity of PEDOT:PSS, it is found that CO2 pulsed laser thermal treatment have advantages in PEDOT:PSS thermal treatment in small area without air controled. In this study, a promising method of heat treatment for PEDOT:PSS is investigated. The conductivity of PEDOT:PSS is enhanced to 59.4 S/cm in air by CO2 Laser, which is much better than hotplate. With the advantage of selective treatment, the heat can be controled for more complicated electrical stucture in the future.

碩士
國立中山大學
高階經營碩士班
93
Cutaneous laser and intense pulsed light treatments are two of the most popular aesthetic treatment modalities. More and more physicians regardless of their training background are providing such profitable services because there is still no regulation on the cosmetic procedures a physician can perform. The purpose of the present study was to find out the relative strength and weakness of different medical specialties in providing laser and intense pulsed light treatment. Major decision factors for physician selection were extracted from 19 physician choice criteria with factor analysis. Using analytic hierarchy process, the relative weight of these factors and that of dermatologists, plastic surgeons and aesthetic practitioners in each factor were calculated. After reading the training curricula of dermatologists and plastic surgeons, respondents were asked to rate again the 3 medical specialties. Our results indicated that medical competence (0.3296) was the most important major decision factor followed by recommendation (0.2198), friendliness (0.1350), cost (0.1307), complete service (0.0984) and physical attribute of the physician (0.0865). Compared with plastic surgeons and aesthetic practitioners, dermatologists had an advantage in all factors except complete service, which was the strength of plastic surgeons. New patients, aged under 40, with a college degree and a monthly allowance less than 20000 NTD were more likely to change their rating in favor of dermatologists after reading the curriculum profile..

碩士
國立交通大學
電子工程系
91
Since high temperature post-annealing for ferroelectric materials was usually required to get the fine crystallinity and ferroelectric characteristics. But many trouble issues was induced by the high thermal budget, such as the inter-diffusion of ferroelectric and substrate, and the deformation of junction profile etc. Therefore it is essential for the reduction of post-annealing temperature in order to make the ferroelectric material compatible the Si-base fabrication process. In this these, low temperature and low thermal budget for fabrication and post-annealing methods are introduced in this thesis. The (Pb,Sr)TiO3 (PST) ferroelectric material with low crystallization temperature was deposited onto the Pt/Ti/Ox/Si substrate for the research of capacitor type 1T-FeRAM. The PST thin film was fabricated by pulse-laser-deposition (PLD) method at low substrate temperature 200oC. At first, the results of conventional post annealing methods (Rapid Thermal Annealing (RTA), Furnace Annealing (FA) were acquired, witch surface cracks and interface lift were found by lager thermal stress. Therefore, novel post-treatment for Excimer Laser Annealing (ELA) method was introduced to suppress the above troubles. The PST thin films were irradiated with conditions of different laser energy density and shot number at low substrate temperature 300oC. The improvement of ferroelectric characteristic was apparently observed from electrical measurement and physical analysis, and it is further inferred that the crystallization phenomenon was occurred only on the surface region. The better improvement for crystallinity was found by appropriate control of laser energy density and shot number. Besides the larger improvement on crystallinity and characteristic of whole thin film were obtained with the combination of ELA and RTA post-treatment. The fine reliability properties for PST thin film with treatment of combination of ELA and RTA method were acquired after Fatigue, Imprint, and TDDB tests. Finally, the better crystallization and ferroelectric characteristic of the whole PST thin film treatments had been successfully achieved under low temperature post-treatment, and it is excellent for the most promising candidate in capacitor type 1T-FeRAM applications.

This study demonstrates an experimental investigation into the efficacy of a novel surface pre-treatment technique to improve the toughness and energy dissipation of composite CFRP T-joints. This novel technique optimizes CO2 laser irradiations to remove surface contaminations and modify the surface morphology of CFRP T-joint adherents. Pull-off tests were performed on T-joints that experienced peel-ply (PP) treatment and to those that were ablated with 10% (LC) and 30% (LA) laser power respectively. A further developed alternative pattern between LA and LC surface pre-treatment was examined. Two different quasi-isotropic stacking sequences have been studied by having surface fibers aligned in 0° and 45° direction. A series of surface roughness analysis, optical microscopy, SEM, CT scan and pictorial findings have been carried out to characterize the surface morphologies and failure modes prior to and after the failure. The patterning technique promoted non-local damage mechanisms which resulted in large improvements in the toughness and energy dissipation as compared to the other pre-treatment techniques. Up to ~12 times higher energy dissipation compared to peel-ply pre-treated T-joint were achieved with patterned T-joint structures that are stacked with a 0° surface fiber direction.

This study demonstrates an experimental investigation into the efficacy of a novel surface pre-treatment technique to improve the toughness and energy dissipation of composite CFRP T-joints. This novel technique optimizes CO2 laser irradiations to remove surface contaminations and modify the surface morphology of CFRP T-joint adherents. Pull-off tests were performed on T-joints that experienced peel-ply (PP) treatment and to those that were ablated with 10% (LC) and 30% (LA) laser power respectively. A further developed alternative pattern between LA and LC surface pre-treatment was examined. Two different quasi-isotropic stacking sequences have been studied by having surface fibers aligned in 0° and 45° direction. A series of surface roughness analysis, optical microscopy, SEM, CT scan and pictorial findings have been carried out to characterize the surface morphologies and failure modes prior to and after the failure. The patterning technique promoted non-local damage mechanisms which resulted in large improvements in the toughness and energy dissipation as compared to the other pre-treatment techniques. Up to ~12 times higher energy dissipation compared to peel-ply pre-treated T-joint were achieved with patterned T-joint structures that are stacked with a 0° surface fiber direction.

碩士
國立中央大學
機械工程研究所
91
The physical processes of laser-tissue interactions are investigated theoretically. The radiative transfer equation (RTE) is used to simulate the laser propagation in tissues. The model includes emission, absorption and anisotropic scattering mechanisms. The RTE is solved by using the discrete — ordinates method. The energy equation is solved by the control volume based finite different method. The resulting numerical code, written in Fortran, is validated by comparing the results with available experimental measurements. The effects of several important parameters on the coagulation and ablation depths of tissue are studied. Results show that the ablation depth increases with the incidence fluence. The pulse frequency of the laser has small influence on the ablation depth. On the other hand, the ablation depth is not affected by t he pulse duration. Laser energy lasers are also used in thermal treatment of skins. In this work, skins are separated into four layers, namely, stratum corneum, epidermis, dermis, and subcutaneous tissue. The results show that, under laser irradiation, the temperature difference between the skin surface and the dermis layer is very large. For better control of affected area, appropriate pulse duration should be used. For applications in photodynamic therapy (PDT), the energy distribution in tissue during the treatment period is investigated. Increasing the absorption coefficient of the tumor leads to higher energy density in the tumor region, this is beneficial fort PDT. The effective attenuation coefficient of the surrounding tissue has profound in influence on the treatment results.

abstract: Objective: Examine cardiovascular response to OMT via central and peripheral measurements. Methods: Central and peripheral cardiovascular signals of asymptomatic human subjects were monitored during a procedure with alternating rest and active phases. Active phases included systemic perturbations and application of controlled vertebral pressure (OMT) by an experienced osteopathic physician. Pulse plethysmograph and laser Doppler flow sensors measured peripheral flow from index and middle fingers bilaterally. A three-lead EKG monitored cardiac activity. The biosignals were recorded continuously, in real time, and analyzed in time and frequency domains. Results from the control group (n=11), without OMT, and active group (n=16), with OMT, were compared. Peripheral (n=5) and central responders (n=6), subsets of the active group showing stronger peripheral or central response, were examined. In an additional effort, a modified clinical device recorded spectral Doppler ultrasound signals of the radial and dorsalis pedis arteries of clinically asymptomatic human subjects. Controlled physiologic provocations (limb occlusion and elevation), were performed. Time domain and spectral analyses were completed. Results: In the human subject study, the time wave characteristics and spectral analysis resulted in similar trends. Peripheral blood flow attenuated in the control group over time, while it was maintained in the active group, and increased specifically during OMT in the responder groups. Heart rate remained around 65 BPM in the control group, fluctuated between 64-68 BPM in the active group, and dropped 4 and 3 BPM in the peripheral and central responder groups, respectively. The effect in the OMT group was statistically significant compared to no-OMT, however, was not statistically significant within-groups. For the preliminary spectral ultrasound Doppler study, segmental flow was successfully monitored. A prototype "Quick Assessment" tool was developed, providing instant post-processing results for clinical use. Conclusions: OMT along the vertebral column may influence autonomic processes that regulate heart rate and peripheral vascular flow.
Dissertation/Thesis
Masters Thesis Bioengineering 2014