京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第21216号 / 情博第669号 / 新制||情||115(附属図書館) / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 守倉 正博, 教授 大木 英司, 教授 梅野 健 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

Laser induced damage is of interest in studying the transmission of large amounts of optical energy through step-index, large core multimode fibers. Optical fibers often have to be routed around objects when laser light is being transmitted between two locations which require the fiber to bend into a curve. Depending on how tight the bend is, this can result in transmission losses or even catastrophic damage when the energy density of the laser pulse exceeds the damage threshold of silica glass. The purpose of this study is to: Establish a minimum bend radius that would allow high energy (GW/cm2 ) to be transmitted through multimode fiber. Evaluate unique fiber routing configurations including loops, 180 bends, and S-bends. Develop optical modeling simulations backed with experimental data that can serve to predict critical areas for future systems. Waveguide theory predicts that light traveling through a bend will form whispering-gallery modes that propagate through total internal reflection bounces along the inside of the outer edge of the bend. This is critical since in these locations the energy density of the light will increase significantly, raising the potential of laser damage, nonlinear effects, and transmission losses. This loss is especially problematic when two 90° bends going in opposite directions are in close proximity to each other, forming an ‘S-bend’. Light that is grouped along the outer edge going through the first bend will enter the second bend at a sharper angle which causes much high transmission losses and raises the possibility of failure. iv Models using R-Soft BeamProp and Zemax were developed to study transmission losses, investigate light interactions at critical areas, and predict under which conditions laser damage would occur. BeamProp presents a clearer view of the modal distribution of light within the core of the fiber and is used to analyze how a plane wave with a Gaussian intensity distribution excites the fiber modes. Zemax provides a tool to perform non-sequential ray tracing through the fiber cable and stray light analysis within the core and once the light exits the fiber. Intensity distributions of the cross sectional area of the fiber shows the whispering gallery modes forming as the light propagates around bends and disburses as it propagates afterwards. It was discovered using R-Soft that if the separation distance between bends in an S-bend is approximately 3 mm there exists a condition where maximum transmission occurs. For 365 µm diameter core fiber it was calculated that the difference in output power could be as high as 150%. This was initially completely unexpected; however ray tracing using Zemax was able to verify that this distance allows the light to transition so that it enters the 2nd bend at the optimal angle to enter the whispering gallery mode. Experiments were performed that validated the models’ predictions and images were captured clearly showing the spatial distribution shift of the light within the core of the fiber. Experiments were performed to verify light grouping together to form whispering gallery modes as predicted by Zemax. Microscope images were taken as a function of distance from various bends to observe the periodic nature in which the laser light fills up the fiber. Additionally, a configuration was setup to examine stimulated Brillioun scattering and determine the onset of laser damage in the fiber. Fibers were tested as a function of bend radius and number of shots v and recommendations for future systems were made. Lastly, mechanical failure tests were performed to determine the relationship between stress placed on the fiber through bending and fiber lifetime in a static environment. This allowed a minimum safe bend radius to be calculated for a 30 year lifetime that agreed with previous calculated values.

Durch die Kopplung von Szintillationskristallen an Lichtwellenleiter könnten robuste Messgeräte für die spektroskopitsche Messung von Strahlungsfeldgrößen in Bohrlöchern in Betonstrukturen beim Rückbau von Kernkraftwerken realisiert werden. In dieser Arbeit wurden zwei Prototypen solcher Messgeräte entwickelt, wobei ein auf einem Gadolinium-Aluminium-Gallium-Granat-Szintillationskristall basierendes Messsystem mit einem Kunststofflichtwellenleiter mit hohem Durchmesser aufgrund seiner hohen Zählrate bevorzugt wurde. Mit diesem Messystem konnten spektroskopische Messungen von Gammastrahlung durchgeführt werden. Weiterhin konnte gezeigt werden, dass Kontaminationen einer bestimmten Aktivität bis in einen Abstand von mehreren Zentimetern von der Messsonde im Beton nachweisbar sind. Ein Schätzwert der minimale Messzeit zur Erkennung einer nachweisbaren Kontamination konnte bestimmt werden. Eine hinreichend große, gemessene Ereigniszahl ermöglicht zusätzlich die Bestimmung des Abstands einer radioaktiven, punktförmigen Kontamination eines bekannten Nuklids. Für ein bekanntes Nuklid konnte weiterhin aus der Zählrate ein Schätzwert für die Energiedosis am Ort der Messsonde mithilfe von Referenzmessungen der Dosis mittels Berylliumoxid-Detektoren bestimmt werden.:Inhaltsverzeichnis Abbildungsverzeichnis vii Tabellenverzeichnis ix 1 Einleitung 1 2 Physikalische Grundlagen 3 2.1 Radioaktiver Zerfall 3 2.2 Gröÿen des Strahlungsfelds 3 2.3 Wechselwirkungen von Photonen mit Materie 5 2.4 Lichtentstehung in anorganischen Szintillatoren 8 2.5 Lichtmessung 10 2.6 Pulshöhenverteilungen von Szintillationsdetektoren 12 2.7 Ein ussfaktoren der Lichtausbeute 14 3 Material und Methoden 16 3.1 Aufbau LSO-Sonde und Messungen mit radioaktiven Quellen 16 3.2 Aufbau Lichtkopplung mittels Linse 18 3.3 Aufbau und Versuchsablauf Quarzglaskopplungen 20 3.4 Aufbau GAGG-Sonde 21 3.5 Aufbau des Betonphantoms 24 3.5.1 Dichtebestimmung des Betonphantoms 24 3.6 Messablauf Tiefenkurven in Betonphantom 27 3.7 Datenanalyse mittels Kolmogorv-Smirnov-Test 27 4 Ergebnisse 29 4.1 Spektroskopische Eigenschaften LSO-Sonde 29 4.2 Winkelverteilung austretender Photonen aus Szintillationskristall 33 4.3 Quarzglaskopplung 36 4.4 Spektroskopische Eigenschaften GAGG-Sonde 43 4.5 Vergleich GAGG- und LSO-Sonde 47 4.6 Abstandsabhängigkeit der Zählrate 50 4.7 Abschätzung der maximalen Abschirmdicke von Beton für Kontaminationserkennung 53 4.8 Abschätzung der minimalen Messzeit zur Kontaminationserkennung 56 4.9 Abschirmungsdickenbestimmung mittels Abschirmungsparameter 57 4.10 Bestimmung der Dosis 62 5 Diskussion 64 6 Zusammenfassung 67 / A robust measuring system for spectroscopic measurementes of gamma-ray radiation in boreholes in concrete structures can be built by coupling of a scintillation crystal to a light guide. Two prototypes of such measuring systems are developed one based on a Gadolinium-Aluminium-Gallium-Garnet scintillation crystal with a plastic optical fiber with a high diameter is preferred due to the higher count rate. Spectroscopic measurements of gamma-ray radiation with this measuring system can be performed. It can be shown that contamination of a specific activity can be detected even if they are located in concrete in a distance of several centimeters from the radiation sensor. for the minimal measurement time of 38 s An estimated value to detect a traceable contamination could be determined. If a high number of events can be detected, even the distance between a point like radioaktive source of a known nuclide and the radiation sensor can be determined. An estimated value for the applied dose at the place of the radiation sensor could be determined for a known nuclide with the help of the count rate. Therefore, reference measurements of dose with berylliumoxide detectors were performed.:Inhaltsverzeichnis Abbildungsverzeichnis vii Tabellenverzeichnis ix 1 Einleitung 1 2 Physikalische Grundlagen 3 2.1 Radioaktiver Zerfall 3 2.2 Gröÿen des Strahlungsfelds 3 2.3 Wechselwirkungen von Photonen mit Materie 5 2.4 Lichtentstehung in anorganischen Szintillatoren 8 2.5 Lichtmessung 10 2.6 Pulshöhenverteilungen von Szintillationsdetektoren 12 2.7 Ein ussfaktoren der Lichtausbeute 14 3 Material und Methoden 16 3.1 Aufbau LSO-Sonde und Messungen mit radioaktiven Quellen 16 3.2 Aufbau Lichtkopplung mittels Linse 18 3.3 Aufbau und Versuchsablauf Quarzglaskopplungen 20 3.4 Aufbau GAGG-Sonde 21 3.5 Aufbau des Betonphantoms 24 3.5.1 Dichtebestimmung des Betonphantoms 24 3.6 Messablauf Tiefenkurven in Betonphantom 27 3.7 Datenanalyse mittels Kolmogorv-Smirnov-Test 27 4 Ergebnisse 29 4.1 Spektroskopische Eigenschaften LSO-Sonde 29 4.2 Winkelverteilung austretender Photonen aus Szintillationskristall 33 4.3 Quarzglaskopplung 36 4.4 Spektroskopische Eigenschaften GAGG-Sonde 43 4.5 Vergleich GAGG- und LSO-Sonde 47 4.6 Abstandsabhängigkeit der Zählrate 50 4.7 Abschätzung der maximalen Abschirmdicke von Beton für Kontaminationserkennung 53 4.8 Abschätzung der minimalen Messzeit zur Kontaminationserkennung 56 4.9 Abschirmungsdickenbestimmung mittels Abschirmungsparameter 57 4.10 Bestimmung der Dosis 62 5 Diskussion 64 6 Zusammenfassung 67

Plants secrete peptide ligands and use receptor signaling to respond to stress and control development. Understanding these phenomena is key to improving plant health and productivity for food, fiber, and energy applications. Phytosulfokine (PSK), a sulfated peptide hormone, regulates plant cell division, growth, and stress tolerance via specific phytosulfokine receptors (PSKRs). This study uses fiber-optic fluorescence microscopy to elucidate trafficking of PSK in live plants. The microscope features two-color optics and an objective lens connected to a 1-m coherent imaging fiber mounted on either a conventional upright microscope body or 5-axis positioning system (X–Y–Z plus pitch and yaw). PSK and fluorescently-labelled PSK were delivered into roots and leaves of various Arabidopsis thaliana genotypes, and their movement was non-destructively tracked with the microscope. High-resolution (3–5 µm) epifluorescence micrographs confirmed that PSK is mobile in plants and levels of PSKR1, PSKR2, or both may impact the trafficking of PSK.

No description available.

No description available.

Beneath North America's roads lie 1.6 million miles of pipeline that provides users with potable water and carry away wastewater. These buried infrastructure systems have been functioning for duration longer than their intended design life, often with little or no repair. Asset management of pipeline systems pose a major challenge for most municipalities due to budgetary constraints, demand for quality service, and need to preserve existing pipeline infrastructure. The first step in developing and implementing a comprehensive asset management plan is to perform a condition assessment. There is a gamut of inspection and monitoring technologies available to enable the condition assessment of pipelines. All of these have advantages and limitations, which determine the performance quality and effectiveness of an individual technology for particular utility assets. Unfortunately, utilities choose technologies not suitable for their specific assets and collect data that is not useful for understanding the condition of their system. The objective of this thesis is to develop a framework for the effective selection of condition assessment technologies for water and wastewater utilities. A Microsoft-Excel based framework is developed to help the utility managers in selecting condition assessment technologies for their water and wastewater pipeline assets. The recommended tool selection approach uses a multi-step exclusion protocol in which the tools are excluded on the basis of their applicability relating to technical feasibility and technical suitability for a particular situation. Usable tools are then compared against a performance and cost database to determine performance and cost in a given project/ utility condition. This thesis provides a brief description and review of 24 non-destructive commercialized condition assessment technologies, including the principal and implementation considerations. A framework for decision system tool was developed to facilitate utilities in selecting appropriate condition assessment technologies. This framework could facilitate the selection of usable technologies by excluding the options which are not technically feasible and suitable. The user can then further explore the usable tools and determine the most suitable technologies for their assets. The data considered in the research is provided by technology providers, thus it may lack complete understanding of the capabilities and limitations of technology. This thesis also presents a case study which highlights the existing gap between the understanding of capabilities and limitations of various technologies. A program is developed as a part of this thesis, Condition Assessment Selection Tool (CAST), which consists of performance and economic database, a graphical user interface to facilitate user input, and the results of the comparison of each usable technology in the database to the project information provided by the user for their assets. The results are presented as performance indices and economic indices indicating the performance and technology cost of usable technologies. A data reliability index was also developed to provide a scale for comparing the reliability of the existing data in the database. / Master of Science

A fatigue test has been performed on 7075-T651 aluminum specimens which were bonded with polyimide coated optical fibers with discrete Bragg gratings. These fibers were bonded with AE-10 strain gage adhesive. The results indicate that lower strain amplitudes do not produce cause for concern, but that larger strain amplitudes (on the order of 3500 μ) may cause some sensors to become unreliable. The strain response of acrylate coated optical fiber strain sensors bonded to aluminum specimens with AE-10 and M-Bond 200 strain gage adhesives was investigated with both axial and cantilever beam tests. These results were compared to both the strain response of conventional strain gages and to model predictions. The results indicate that only about 82.6% of the strain in the specimen was transferred through the glue line and fiber coating into the fiber. Thus, multiplying by a strain transfer factor of approximately 1.21 was sufficient to correct the optical fiber strain output. This effect was found to be independent of the adhesive used and independent of the three-dimensional profile of the glue line used to attach the fiber. Finally, this effect did not depend on whether the fiber had a polyimide or an acrylate coating. Further investigation was conducted on the feasibility of using optical fiber strain sensors for monitoring subcritical damage (such as matrix cracks) in fiber reinforced composite materials. These results indicate that an array of optical fibers which monitor the strain profile on both sides of a composite panel may be sufficient for these purposes / Master of Science

Asynchronous multiplexing schemes are efficient than synchronous schemes, in a bursty traffic environment of multiple access local area network (LAN), as fixed bandwidth is not allocated among the users and there is no access delay. Fiber- Optic Code-Division Multiple Access (FO-CDMA) is one such asynchronous multiplexing scheme suitable for high speed LAN networks. While FO-CDMA offers potential benefits it also faces challenges in three diverse areas which are 1) coding algorithms and schemes 2) advanced encoding and decoding hardware and 3) network architecture. In this thesis, as a solution to the first challenge, we propose the design and construction of a new family of codes, wavelength/time multiple-pulses-per-row (W/T MPR) codes. These codes have good cardinality, spectral efficiency and minimal cross-correlation values. Performance analysis of the W/T MPR codes is carried out and found to be superior to other codes. In unipolar 1-D Optical Orthogonal Codes (OOCs) proposed by Salehi et al., the ratio of code length/code weight grows rapidly as the number of users is increased for a reasonable weight. Hence, for a given pulse width, the data rate decreases or in other words for a given data rate very narrow pulses have to be used, because of which dispersion effects will be dominant. To overcome the drawbacks of non-linear effects in large spread sequences of 1-D unipolar codes in FO-CDMA networks, several two-dimensional codes have been proposed. Wavelength-time (W/T) encoding of the two-dimensional codes is practical in FO-CDMA networks. W/T codes reported so far can be classified mainly into two types: 1) hybrid sequences, where one type of sequence is crossed with another to improve the cardinality and correlation properties and 2) matrix codes, 1-D sequences converted to 2-D codes or 2-D codes by construc- tion, to reduce the ’time’ spread of the sequences/codes. Prime-hop and eqc/prime W/T hybrid codes have been proposed where one type of sequence is crossed with another to improve the cardinality and correlation properties. Other constructions deal with conversion of 1-D sequences to 2-D codes either by using Chinese remainder theorem or folding GoLomb rulers. W/T single-pulse-per-row (W/T SPR) codes are 2-D codes constructed using algebraic method Addition Modulo Group operation. Motivation for this work: To design a family of 2-D codes which have the design choice of length of one dimension over the other, and also have better cardinality, spectral efficiency and also low cross-correlation values (thereby have low BER) than that of the reported unipolar 2-D codes. In this thesis, we describe the design principles of W/T MPR codes, for in- coherent FO-CDMA networks, which have good cardinality, spectral efficiency and minimal cross-correlation values. Another feature of the W/T MPR codes is that the aspect ratio can be varied by trade off between wavelength and temporal lengths. We lay down the necessary conditions to be satisfied by W/T MPR codes to have minimal correlation values of unity. We analytically prove the correlation results and also verify by simulation (of the codes) using Matlab software tool. We also discuss the physical implementation of the W/T MPR FO-CDMA network with optical encoding and decoding. We show analytically that when distinct 1-D OOCs of a family are used as the row vectors of a W/T MPR code, it will have off-peak autocorrelation equal to ‘1’. An expression for the upper bound on the cardinality of W/T MPR codes is derived. We also show that 1-D OOCs and W/T SPR codes are the limiting cases of W/T MPR codes. Starting with distinct 1-D OOCs, of a family, as row vectors, we propose a greedy algorithm, for the construction of W/T MPR codes and present the repre- sentations of the results. An entire W/T MPR code family, generated using greedy algorithm, is simulated for various number of interfering users. Performance analysis of the W/T MPR codes and their limiting cases is carried out for various parameter variations such as the dimensions of wavelength, time and weight of the code. We evaluate the performance in terms of BER, capacities of the networks, temporal lengths needed (to achieve a given BER). Multiple access interference (MAI) signal can be reduced, by using a bistable optical hard-limiter device in the W/T MPR code receiver, by eliminating those signal levels which exceed a certain preset level. Performance analysis of the W/T MPR codes and their limiting cases is studied for various parameter variations. For given wavelength × time dimensions, we compare various W/T codes, whose cardinalities are known, and show that W/T MPR family of codes have better cardinality and spectral efficiency than the other (reported) W/T codes. As W/T MPR codes are superior to other W/T codes in terms of cardinality, spectral efficiency, low peak cross-correlation values and at the same time have good performance, makes it a suitable coding scheme for incoherent FO-CDMA access networks.

This thesis deals with theoretical description of fiber-optic angular velocity sensors, or gyroscopes, and further with design and construction of own sensor of this type. The theoretical part describes problematics of interferometric and resonant fiber-optic gyroscopes. Basic principles and physical limits are described for both types. The main focus is then put on analysis of possible conceptions of these sensors. Solutions using different optical configurations as well as various modulation and signal processing schemes are discussed. The practical part deals with design and construction of own interferometric fiber-optic gyroscope in closed-loop configuration. The gyroscope utilizes all-fiber components including piezoelectric phase modulator and unexpensive single-mode fiber, which are commonly used only for open-loop configurations. To realize closed-loop operation, special modulation scheme based on fully harmonic signal was develeped, which yields linear output within wide dynamic range. This type of modulation requires high level of synchronization achieved by using a field-programmable gate array module. The gyroscope utilizes powerful broadband fiber source, polarizer and Lyot depolarizer which ensure good reciprocity of whole architecture. The parameters of the sensor, obtained by measurement, are even comparable to some sensors using PM fiber, which is much more expensive.