In zukünftigen kerntechnischen Anlagen können die Materialien Blei und Bismut eine größere Rolle spielen als heute. Für die Planung dieser Anlagen werden verlässliche Wirkungsquerschnittsdaten benötigt. Insbesondere der Neutronentransport in einem Blei-Spallationstarget eines beschleunigergetriebenen unterkritischen Reaktors hängt stark von den inelastischen Streuquerschnitten im Energiebereich von 0,5 MeV bis 6 MeV ab. In den vergangenen 20 Jahren wurden elastische und inelastische Neutronenstreuquerschnitte mit hoher Präzision für eine Vielzahl von Elementen am PTB-Flugzeitspektrometer gemessen. Zur Erzeugung der Neutronen wurde hauptsächlich die D(d,n)-Reaktion genutzt. Aufgrund des Q-Wertes der Reaktion und der verfügbaren Deuteronenenergien können Neutronen im Energiebereich von 6 MeV bis 16 MeV erzeugt werden. Die Messung von Wirkungsquerschnitten bei niedrigeren Energien erfordert somit die Verwendung einer anderen neutronenerzeugenden Reaktion. Hierfür wurde die 15N(p,n)15O-Reaktion ausgewählt, da sie die Erzeugung monoenergetischer Neutronen bis zu einer Energie von 5,7 MeV erlaubt. In dieser Arbeit wird die 15N(p,n)-Reaktion auf ihre Eignung als Quelle monoenergetischer Neutronen in Streuexperimenten untersucht. Die Untersuchung der Reaktion beinhaltet die Messung von differentiellen Wirkungsquerschnitten für ausgewählte Energien und die Auswahl von optimalen Targetbedingungen. Differentielle elastische und inelastische Neutronenstreuquerschnitte wurden unter Anwendung der Flugzeitmethode für Blei bei vier Energien zwischen 2 MeV und 4 MeV gemessen. Eine Bleiprobe mit natürlicher Isotopenzusammensetzung wurde verwendet. Für den Nachweis der gestreuten Neutronen wurden NE213 Flüssigszintillatoren verwendet, deren Nachweiswahrscheinlichkeit gut bekannt ist. Winkelintegrierte Wirkungsquerschnitte wurden mit einem Legendre-Polynomfit unter Verwendung der Methode der kleinsten Quadrate bestimmt. Zusätzlich erfolgten Messungen für die isotopenreinen Streuproben 209Bi und 181Ta bei 4 MeV Neutronenenergie. Die Ergebnisse werden mit denen früherer Experimente und aktuellen Evaluationen verglichen. / In future nuclear facilities, the materials lead and bismuth can play a more important role than in today’s nuclear reactors. Reliable cross section data are required for the design of those facilities. In particular the neutron transport in the lead spallation target of an Accelerator-Driven Subcritical Reactor strongly depends on the inelastic neutron scattering cross sections in the energy region from 0.5MeV to 6 MeV. In the recent 20 years, elastic and inelastic neutron scattering cross sections were measured with high precision for a variety of elements at the PTB time-of-flight spectrometer. The D(d,n) reaction was primarily used for the production of neutrons. Because of the Q value of the reaction and the available deuteron energies, neutrons in the energy range from 6MeV to 16MeV can be produced. For the cross section measurement at lower energies, however, another neutron producing reaction is required. The 15N(p,n)15O reaction was chosen, as it allows the production of monoenergetic neutrons with up to 5.7MeV energy. In this work, the 15N(p,n) reaction was studied with focus on the suitability as a source for monoenergetic neutrons in scattering experiments. This includes the measurement of differential cross sections for the neutron producing reaction and the choice of optimum target conditions. Differential elastic and inelastic neutron scattering cross sections were measured for lead at four energies in the region from 2MeV to 4MeV incident neutron energy using the time-offlight technique. A lead sample with natural isotopic composition was used. NE213 liquid scintillation detectors with well-known detection efficiencies were used for the detection of the scattered neutrons. Angle-integrated cross sections were determined by a Legendre polynomial expansion using least-squares methods. Additionally, measurements were carried out for isotopically pure 209Bi and 181Ta samples at 4MeV incident neutron energy. Results are compared with other measurements and recent evaluations.

RoboRally is a board game where the goal is to drive a small robot from a start position to a goal across a dynamic board with different types of obstacles. The robots in this game aren’t real robots, they are small plastic figures which are moved by hand during the game. Our vision is to research a solution for implementing the game with real robots. In order to do this, precise positioning is key. The purpose of this project was therefore to create a local positioning system that allows a robot to find its position in a defined space and change it on a user command with good precision. The built positioning system is based on the time of flight technique using infrared light and ultrasound. The system uses two transmitters and one receiver to calculate two planar distances which can be converted to a coordinate within the board. To assess the system performance in a RoboRally application a small robot was built and multiple tests conducted. The first result was that a one-dimensional distance calculation using the time of flight technique achieved a mean error of 3,2 mm for distances shorter than 1 m. The next result was that the positioning system achieved a 90 x 70 cm rectangle field of view with an accuracy between 1 and 6 cm within this area. The last result was that the robot was able to move a specified distance with a precision of  ± 1 mm and then verify its position successfully at a rate of 97 %. The final conclusion of the project is that the positioning system is accurate enough for a RoboRally application but needs improvements on its field of view. / RoboRally är ett brädspel som går ut på att köra en robot från en startpunkt till ett mål över en dynamisk spelplan med olika typer av hinder. Robotarna i detta spel är inte riktiga robotar, det är små figurer av plast som flyttas för hand under spelets gång. Vårt mål är att undersöka en lösning för att implementera spelet med riktiga robotar. För att lyckas med detta så är det viktigt med noggrann positionering. Syftet med detta projekt var att skapa ett positioneringssystem som gör att en robot kan hitta sin egen position inom en yta och ändra den på kommando med god precision. Positioneringssystemet som tagits fram är baserat på time of flight teknik med hjälp av infrarött ljus och ultraljud. Systemet använder två sändare och en mottagare för att räkna ut två avstånd som sedan kan omvandlas till en koordinat på spelplanen. För att bedömma systemets prestanda i RoboRally sammanhang så har en liten robot byggts och flera tester utförts. Det första resultatet är att en endimensionell av-ståndsberäkning med time of flight tekniken kunde uppnå ett medelfel på 3,2 mm för avstånd kortare än 1 m. Nästa resultat var att positionssystemet uppnådde ett 90 x 70 cm rektangulärt synfält med en noggrannhet mellan 1 och 6 cm inom detta område. Det sista resultatet var att roboten kan förflytta sig en bestämd sträcka med en noggrannhet p°a ± 1 mm och sedan verifiera sin position korrekt 97 % av försöken. Projektets slutsats är att positionssystemet har tillräckligt bra noggrannhet för att kunna användas för RoboRally men att det behöver förbättrat synfält.

RoboRally is a board game where the goal is to drive a smallrobot from a start position to a goal across a dynamic boardwith different types of obstacles. The robots in this gamearen’t real robots, they are small plastic figures which aremoved by hand during the game. Our vision is to researcha solution for implementing the game with real robots. Inorder to do this, precise positioning is key. The purposeof this project was therefore to create a local positioningsystem that allows a robot to find its position in a definedspace and change it on a user command with good precision.The built positioning system is based on the time offlight technique using infrared light and ultrasound. Thesystem uses two transmitters and one receiver to calculatetwo planar distances which can be converted to a coordinatewithin the board.To assess the system performance in a RoboRally applicationa small robot was built and multiple tests conducted.The first result was that a one-dimensional distancecalculation using the time of flight technique achieveda mean error of 3,2 mm for distances shorter than 1 m. Thenext result was that the positioning system achieved a 90x 70 cm rectangle field of view with an accuracy between1 and 6 cm within this area. The last result was that therobot was able to move a specified distance with a precisionof ± 1 mm and then verify its position successfully at a rateof 97 %.The final conclusion of the project is that the positioningsystem is accurate enough for a RoboRally applicationbut needs improvements on its field of view. / RoboRally är ett brädspel som går ut på att köra en robot från en startpunkt till ett mål över en dynamisk spelplan med olika typer av hinder. Robotarna i detta spel är inte riktiga robotar, det är små figurer av plast som flyttas för hand under spelets gång. Vårt mål är att undersöka en lösning för att implementera spelet med riktiga robotar. För att lyckas med detta så är det viktigt med noggrann positionering. Syftet med detta projekt var att skapa ett positioneringssystem som gör att en robot kan hitta sin egen position inom en yta och ändra den på kommando med god precision. Positioneringssystemet som tagits fram är baserat på time of flight teknik med hjälp av infrarött ljus och ultraljud. Systemet använder två sändare och en mottagare för att räkna ut två avstånd som sedan kan omvandlas till en koordinat på spelplanen. För att bedömma systemets prestanda i RoboRally sammanhang så har en liten robot byggts och flera tester utförts. Det första resultatet är att en endimensionell avståndsberäkning med time of flight tekniken kunde uppnå ett medelfel på 3,2 mm för avstånd kortare än 1 m. Nästa resultat var att positionssystemet uppnådde ett 90 x 70 cm rektangulärt synfält med en noggrannhet mellan 1 och 6 cm inom detta område. Det sista resultatet var att roboten kan förflytta sig en bestämd sträcka med en noggrannhet på ± 1 mm och sedan verifiera sin position korrekt 97 % avförsöken. Projektets slutsats är att positionssystemet har tillräckligtbra noggrannhet för att kunna användas för RoboRally men att det behöver förbättrat synfält.

This paper describes a method of estimating distance via Time-of-Flight (TOF) measurement using ultrasonic Orthogonal Frequency Division Multiplexing (OFDM) signals. Using OFDM signals allows the signals and their sub-carriers to remain orthogonal to each other while continuously transmitting. This estimation method is based on the change of phase of a traveling wave as it propagates through a medium (air for ultrasonic signals). By using signals containing multiple tones, the phase change between each frequency component is slightly different. This phase difference is dependent on the distance traveled and can thus be used to estimate distance. This paper studies the impact of tone (OFDM sub-carriers) separation on accuracy, maximum distance, and computation for two-tone and three-tone systems. The effects of the transducer channel bandwidth and channel noise are accounted for to build an accurate model for a single-transmitter single-receiver system. This study found that each additional tone provides one extra independent distance measurement which improves accuracy in the presence of noise. The inclusion of an additional tone while maintaining the same overall signal strength shows improved performance with a reduction in standard deviation of estimated distance from 5.64 mm to 3.42 mm in simulation. A four-tone system is also examined to show that this effect holds for additional tones.

No description available.

No description available.

Objectives: Fusobacteria are prominent participants in the maturation of subgingival dental plaque biofilms in humans. A number of various species belonging to the Fusobacterium genus have been recovered from the subgingival microbiota of chronic periodontitis patients. However, conventional Fusobacterium species identification is labor-intensive, time-consuming, and complicated by shortcomings in phenotypic-based classification schemes, where many fusobacteria display overlapping and non-distinguishing morphologic features and biochemical properties. In addition, molecular identification of fusobacteria is plagued with difficulties of validating the specificity of nucleic acid probes and primers to various Fusobacterium species that have closely-related interspecies genetic profiles. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, and its associated analytic software, was recently approved for clinical microbiology diagnostic use by the United States Food and Drug Administration. MALDI-TOF mass spectrometry has the potential to rapidly identify cultivable clinical isolates to a species level for 4,613 different bacterial species based on mass spectra of their bacterial protein profiles, including many Fusobacterium species. The purpose of this study was to use MALDI-TOF mass spectrometry to rapidly identify the patient distribution of fusobacteria isolated from the subgingival microbiota of chronic periodontitis patients. Methods: A total of 34 chronic periodontitis patients provided 96 fresh subgingival cultivable fusobacteria isolates (one to seven isolates per patient), which were presumptively identified by their chartreuse-positive colony autofluorescence under long-wave ultraviolet light on anaerobically-incubated, non-selective, enriched Brucella blood agar primary isolation plates. Each of the presumptive fusobacteria clinical isolates were subjected to MALDI-TOF mass spectrometry analysis using a bench top mass spectrometer, Bruker FlexControl 3.0 software, and MALDI Biotyper 3.1 software (Bruker Daltonics, Billerica, MA, USA), which contains mass spectra for a variety of fusobacteria in its reference library of bacterial protein profiles. Each clinical isolate underwent on-target plate formic acid protein extraction, and was taxonomically classified with MALDI-TOF mass spectrometry within an approximately 30-45 minute time period from the point of colony harvesting from primary isolation culture plates. A MALDI Biotyper log score of equal to or larger than 1.7 was required for reliable taxonomic classification of the clinical fusobacteria isolates. Results: A majority (58.8%) of the chronic periodontitis patients yielded two or three different species of subgingival Fusobacterium on non-selective enriched Brucella blood agar primary isolation plates. Fusobacterium naviforme was identified by MALDI-TOF mass spectrometry analysis in 14 (41.2%) chronic periodontitis study patients, Fusobacterium nucleatum subspecies vincentii in 13 (38.2%) patients, Fusobacterium nucleatum subspecies polymorphum in 9 (26.5%) patients, Fusobacterium nucleatum and Fusobacterium species each in 6 (17.6%) patients, Fusobacterium nucleatum subspecies nucleatum in 4 (11.8%) patients, and Fusobacterium nucleatum subspecies animalis in 3 (8.8%) patients. Three patients additionally yielded subgingival isolates of Fusobacterium canifelinum, normally an inhabitant of the oral cavity of dogs and cats. 52 (54.2%) of the fusobacteria clinical isolates revealed MALDI Biotyper log scores of equal to or larger than 1.7, the threshold for reliable taxonomic classification, while in comparison, 44 (45.8%) had log scores less than 1.7, indicating a less reliable species identification. No other microbial species, other than one of the Fusobacterium species, was listed by the MALDI-TOF mass spectrometry analytic software as the most likely organism for the tested clinical isolates. Conclusions: These findings indicate that a variety of Fusobacterium species may be identified with MALDI-TOF mass spectrometry in the subgingival microbiota of chronic periodontitis patients. F. naviforme and F. nucleatum subspecies vincentii were the most frequently isolated subgingival fusobacteria species in the evaluated study patients. Three chronic periodontitis patients also unexpectedly revealed subgingival isolates of the animal species F. canifelinum, which is normally in the oral cavity of dogs and cats. MALDI-TOF mass spectrometry may facilitate rapid identification of cultivable fusobacteria in human subgingival dental plaque biofilms, and enhance understanding of bacterial community structure in periodontal pockets. / Oral Biology

Laser-Ionization Time-of-Flight Mass Spectrometry (LI-TOF-MS) is a sophisticated tool for the molecular-weight determination and structural characterization of a variety of molecules. Advances in instrumentation and ionization methods have recently expanded its role in the analysis of high-mass analytes. Large multimetallic complexes, which are efficient solar-energy converters, rely heavily on their chemical structure for optimum operation. Molecular mass determinations of these multimetallic complexes have been problematic due to their lability and high molecular weights. This thesis describes the characterization of a LI-TOF-MS instrument and confirmation of theoretical time-of-flight mass-separation principles. Several test cases demonstrate the instrument's proper operation and calibration for a wide mass range of analytes. Mass spectral results of three organometallic compounds: i. [Ir(dpp)₂Cl₂](PF₆), ii. {[(bpy)₂Ru(dpp)]₂IrCl₂}(PF₆)₅, and iii. {[(bpy)₂Ru(dpp)]₂RuCl₂}(PF₆)₅ under a variety of laser ionization and sample preparation conditions are compared. A complete structural characterization of the monometallic complex, [Ir(dpp)₂Cl₂](PF₆), is presented. The two trimetallic analytes fragmented easily, but significant components of the molecules are successfully identified. After optimizing the ionization and analytical procedure, LI-TOF-MS proved useful in the analysis of high molecular mass metal complexes. / Master of Science

[pt] Os Ensaios Não-Destrutivos são técnicas utilizadas na inspeção de materiais e equipamentos sem dano a integridade física, podendo ser executados nas etapas de pós-fabricação, montagem, operação e manutenção. São utilizados pela indústria como ferramenta de controle e garantia da qualidade de materiais, produtos e processos. Esta pesquisa teve como objetivo identificar trincas e estimar o seu comprimento em corpos de prova de aço DIN 42CrMo4, adotando diferentes técnicas de END. Os corpos de prova foram de um eixo virabrequim de um motor Diesel, utilizado como unidades geradora em usinas termoelétricas, que falhou por fadiga de baixo ciclo. Os corpos de prova foram projetados de acordo com as normas ASTM E1820, ASTM E1290 e ISO 15653, bem como adotando sugestões de inspetores de ultrassom quanto a uma geometria que otimizasse a eficiência das medições. Subsequente ao trincamento dos corpos de prova em fadiga, os mesmos foram inspecionados com o emprego das técnicas de Radiografia Digital (RD), Ultrassom Phased Array (UT-PA), métodos Pulso-Eco (PE) e Time os Flight Diffraction (TfOD), e Tomografia Computadorizada (TC). Em sequência, os corpos de prova foram fraturados com o uso de uma carga em flexão e nitrogênio liquido, o que permitiu a medição real dos comprimentos das trincas. As técnicas de UTPA, RD e TC indicaram tamanhos de trincas próximos entre si. Nos métodos de PE e ToFD, de UT-PA, se observou que a indicação das trincas sofre influência da distancia entre o cabeçote do equipamento e a posição da trinca. Em trincas menores, essa influência é mais acentuada, levando a uma medição errônea do comprimento da trinca. A técnica de RD apresentou um bom resultado da medida lateral da trinca, porem foi necessário um processamento digital da imagem para obtenção de melhores resultados, explicado devido a sensibilidade do ensaio à geometria do corpo de prova e da densidade do material utilizado. Já a TC apresentou imagens melhores e medidas de trinca similares se comparada com a RD, o que pode influenciar em outros tipos/dimensões de defeitos. Em compensação, sofre mais influencia do volume de material presente no entorno do defeito, o que impossibilitou a detecção de defeitos em algumas amostras. / [en] Non-Destructive Testing (NDT) are techniques applied to materials and equipment inspection without integrity degradation and can be performed in the post-manufacture, assembly, operation and maintenance stages. Those techniques are used by the industry to control a guarantee the quality of materials, products and processes. The aim of this research was to identify cracks and estimate their length on DIN 42CrMo4 steel specimens adopting different NDT techniques. The material to the test specimen was taken from a crankshaft of a Diesel engine, utilized as generating units in thermoelectric power plant, which has failed due to low cycle fatigue. The test specimen were designed according to ASTM E1820, ASTM E1290 and ISO 15653 standards, as well as suggestions made by NDT inspectors for a geometry that optimized the efficiency of the measurement. Subsequent to the fatigue induced crack on the specimens, they were inspected using, Digital Radiography (RD), Phased Array Ultrasound (UT-PA), Pulse-Echo (PE) and Time of Flight Diffraction (ToFD) methods, and Digital Tomography (TC). The specimens were then fractured with a bending load and liquid nitrogen, which allowed the measurement of the real crack length. UT-PA, PE and ToFD, and RD techniques showed a closer estimate crack size among then. It was observed that both UT-PA methods, PE and ToFD, presented an influence of the distance between the equipment head and the crack position, on the crack measurement. This was more pronounced in smaller cracks, leading to an erroneous measurement of the crack length. The RD technique presented a good a good result of lateral crack length, but a good digital image processing was necessary to obtain these results, explained by the sensitivity of the test to the geometry to the geometry of the specimen and to the material density. TC presented better imaging and similar lateral crack lengths when compared to RD, which could influence the detection of other types/dimensions of defects. In contrast, it is more influenced by the volume of material around the object, which made it impossible to detect defects in some samples.

Depuis quelques années, la thématique de la localisation a connu un regain d’intérêt,motivé en grande partie par le développement des réseaux de capteurs sans fil. Lespropositions ayant pour objectif d’apporter une réponse à cette problématique peuvent êtreclassées en deux catégories : les méthodes range-based, retenues pour cette thèse, dont lacaractéristique est de se fonder sur des mesures en temps réel du signal pour générer uneestimation relativement fiable de la distance, et les solutions range-free, économes enressources car se limitant à l’exploitation d’hypothèses concernant la connectivité des noeudsdans le réseau. Les contributions peuvent se focaliser sur l’un des trois aspects fondamentauxde la question : le développement d’une couche physique performante, la proposition d’unalgorithme de calcul permettant des résultats plus précis, et la mise en place d’un protocole decollecte de mesures.La contribution de cette thèse est par conséquent multiple : en premier lieu, nousproposons un nouveau protocole de mesure du temps de vol, nommé Parallel SymmetricDouble-Sided Two-Way Ranging (PSDS-TWR), dont l’objectif est la réduction de la chargeprotocolaire du service. Deuxièmement, nous avons mis en place un algorithme de calcul dela position désigné par interRing Localization Algorithm (iRingLA). Basé sur une recherchelinéaire, iRingLA accepte des données inexactes et en extrait une estimation de la positiondont l’erreur est inférieure à 2m dans 70% des cas, ceci en s’exécutant directement sur unnoeud mobile léger. Les données concernant l’algorithme ont été collectées grâce à unprototype utilisant la technologie Chirp Spread Spectrum tandis que l’étude de performancedu protocole a impliqué la conception d’un simulateur nommé DokoSim / The development of Wireless Sensor Networks has given a new life to research in thefield of localization. Many proposals have been made which can be classified as either rangefreeor range-based solutions. The range-free category relies on a priori knowledge of thenetwork while the latter uses the available hardware to measure signal characteristics fromwhich distance information can be derived. Although the information origin can vary, allproposals either introduce a new protocol, a novel algorithm or a new and improved physicallayer.Our work led to the definition of a new protocol and an efficient algorithm. Aside fromallowing the nodes to collect Time Of Flight related data, the Parallel Symmetric Double-Sided Two-Way Ranging protocol (PSDS-TWR) reduces overhead and energy consumption,making the localization service affordable for the network. The performance of this protocol,in terms of duration, has been studied using a homemade simulator named DokoSim. We alsointroduce an algorithm based on rings and linear search. This inter-Ring LocalizationAlgorithm (iRingLA) achieves a localization error of less than 2m in 70% of the cases whilebeing tested on our Chirp Spread Sprectrum based prototype