<p>For complex technical systems in the electricity and pulp and paper industries, maintenance management addresses how to exploit physical assets in the most profitably way. This is a difficult task that requires taking into consideration parameters of totally different natures – e.g. reliability data, operating costs, condition of technical systems, the environment and rules and regulation.</p><p>An incorrect estimate of a residual lifetime can result in a premature renewal with accompanying high capital costs. If, however, renewal is delayed, a breakdown may occur which can cause major damage to technical equipment and a loss of income due to outages. Because of the complexity of many technical systems, it can be hard to select adequate data to use when making decisions about renewal strategies. To cope with this, one approach is to use less detailed models that are operated by skilled analysts.</p><p>This work demonstrates the advantage of such an approach by proposing two methods applied in a joint methodology that has its origins in RCM. The methodology consists of Dynamic Lifetime Model (DLA) and the Condition Based Index (CBI). The DLA method copes with the financial risk associated with the point in time for when a renewal is carried out and the CBI method uses critical parameters to estimate the condition of a technical system. The two methods together create a quantitative connection between reliability, maintenance and financial risk. A case study based validation of the methodology was carried out at SCA Ortvikens paper mill on a refiner system and Forsmark nuclear power plant. Lessons learned from the case study showed that the methodology could be used to identify which components could cause costly breakdown. By using the methodology a manager gets a decision support tool for estimating short-term and long-term consequences of decisions regarding maintenance management in order to maximize utility of the system concerned</p>

The capability to resolve the contributions from spectroscopically overlapping fluorophores has enabled significant breakthroughs in cellular imaging. However, commercial microscopes for this purpose use analog light detection with least squares curve-fitting analysis and improvements in sensitivity are needed. To this end, a microscope has been constructed with high throughput and single-photon detection capability. The fluorescence is separated through use of a prism spectrometer or a series of dichroic mirrors into four spectral bands and detected using four single-photon avalanche diode (SPAD) detectors, which provide high-quantum efficiency in the red spectral region. The detectors are connected to a time-correlated single photon counting module to provide sub-nanosecond temporal resolution for distinguishing fluorophores with different fluorescence lifetimes. Maximum-likelihood (ML) methods have been developed for analyzing the temporally and spectrally resolved photon count data from the SPADs to find the contributions from different fluorescent species and from background. Commercially available SPADs exhibit a count-rate dependent time shift in the impulse response function, and hence the instrument incorporates custom modified SPADs with improved timing stability. Nevertheless, there is still some time shift, and hence the ML-analysis has been extended to include this as an adjustable parameter for each individual SPAD. Monte Carlo simulations have also been developed to enable studies of the number of photons needed to resolve specific fluorophores.

We have investigated the use of deep UV laser induced fluorescence for the sensitive detection and spectroscopic lifetime studies of terbium doped dipicolinic acid (DPA-Tb) and used this to study the optical characteristics of DPA which is a chemical surrounding most bacterial spores. Background absorption spectra, fluorescence spectra, and Excitation Emission Matrix (EEM) spectra were made of the DPA-Tb complex, using both fixed 266 nm wavelength and tunable (220 nm -- 280 nm) UV laser excitations. Of importance, the fluorescence lifetimes of the four main fluorescence peaks (488 nm, 543 nm, 581 nm, and 618 nm) of the DPA-Tb complex have been measured for the first time to our knowledge. The lifetimes of all the fluorescing lines have been measured as a function of DPA-Tb concentration, solvent pH, and solvent composition, including that for the weakest fluorescing line of DPA-Tb at 618 nm. In addition, a new spectroscopic lifetime measurement technique, which we call "Transient Fluorescence Spectroscopy" was developed. In this technique, a weak, quasi-CW, amplitude modulated UV laser (8.5 kHz) was used to measure the lifetimes of the fluorescence lines, and yields insight into energy transfer and excitation lifetimes within the system. This technique is especially useful when a high power laser is not either available or not suitable. In the latter case, this would be when a high power pulsed deep-UV laser could produce bleaching or destruction of the biological specimen. In addition, this technique simulated the excitation and fluorescence emission of the DPA-Tb using a 4-level energy model, and solved the dynamic transient rate equations to predict the temporal behavior of the DPA-Tb emitted fluorescence. Excellent agreement between the experiments and the simulation were found. This technique has the potential to provide a more accurate value for the fluorescence lifetime values. In addition, with the use of asymmetric excitation waveforms, the dynamic transient rate equation analysis may allow for detailed studies of selected transfer mechanisms in a wide range of other spectroscopic applications including rare-earth solid-state lasing materials and biological samples.

Wireless sensor networks (WSN) are an emerging technology with a wide range of applications including environment monitoring, security and surveillance, health care, smart homes, etc. Subject to severe resource constraints in wireless sensor networks, in this research, we address the distributed estimation of unknown parameters by studying the correlation among resource, distortion, and lifetime, which are three major concerns for WSN applications. The objective of the proposed research is to design efficient distributed estimation algorithms for resource-constrained wireless sensor networks, where the major challenge is the integrated design of local signal processing operations and strategies for inter-sensor communication and networking so as to achieve a desirable tradeoff among resource efficiency (bandwidth and energy), system performance (estimation distortion and network lifetime), and implementation simplicity. More specifically, we address the efficient distributed estimation from the following perspectives: (i) rate-distortion perspective, where the objective is to study the rate-distortion bound for the distributed estimation and to design practical and distributed algorithms suitable for wireless sensor networks to approach the performance bound by optimally allocating the bit rate for each sensor, (ii) energy-distortion perspective, where the objective is to study the energy-distortion bound for the distributed estimation and to design practical and distributed algorithms suitable for wireless sensor networks to approach the performance bound by optimally allocating the bit rate and transmission energy for each sensor, and (iii) lifetime-distortion perspective, where the objective is to maximize the network lifetime while meeting estimation distortion requirements by jointly optimizing the source coding, source throughput and multi-hop routing. Also, energy-efficient cluster-based distributed estimation is studied, where the objective is to minimize the overall energy cost by appropriately dividing the sensor field into multiple clusters with data aggregation at cluster heads.

The results from this study show that it is possible to obtain data series on the steel scrap collection based on mass balance model on the crude steel production figures by steelmaking reactor type and additional knowledge on process metallurgy as well as information on inputs and outputs into the reactors with an area correlation coefficient of 0,91 compared to data obtained from trade statistics. Furthermore, the study shows that based on a new method it is possible to calculate the time duration of mass flows on a continuous basis. Furthermore, two complementary statistical dynamic material flow models that can be used to calculate the societal recycling rates of steel was constructed. These statistical models contribute to a standardized way of obtaining consistent results. The new models are able to segregate the non-recirculated amounts of steel into the hibernating steel stock available for future collection from the amounts of losses based on statistics. The results show that it is possible to calculate the amounts of steel scrap available for steelmaking at a given point in time. In addition, based on the new models it is possible to calculate recycling trends in society. Also, the models are able to calculate robust forecasts on the long-term availability of steel scrap, and test if forecast demand of steel scrap exceeds a full recovery. This due to that the steel scrap generation is a function of the collection rate of steel scrap. Also, a method for obtaining representative samplings on the alloy content in steel scrap called random sampling analysis (RSA) was developed. The results from the RSA show that it is possible to optimize the recovery of valuable elements in the production process of steelmaking based on the information on the composition of steel scrap. / <p>QC 20151020</p>

Cold, trapped atomic ions have enabled the investigation of fundamental physics and generated a rich field of applications. Foremost among these is quantum computation which has recently driven the development of the sophisticated, scalable surface-electrode trap. Despite the many advantages of surface-electrode traps, the typically smaller ion-electrode distance, d, in these traps results in an increased ion heating rate that is proportional to d^(-4) and a decreased trap well-depth that is proportional to d^(-2). These shortcomings can be simultaneously addressed by installing the trap into a cryogenic environment. With this in mind, a closed-cycle, cryogenic ion trapping apparatus that maintains excellent vacuum, is highly modular, has increased optical access, and uses a simple vibration isolation system has been developed. Single ions are trapped and used to characterize system properties such as the motion of the vibration isolation stage. In order to compare this system to a similar room temperature apparatus, the ion trapping lifetime and heating rate are determined. A single ion also serves as a sensitive electric field probe that is used to measure and compensate stray electric fields across the trap. Due to the long dark ion lifetimes in this system, it is well-suited to probing the stability of small, linear ion crystals. Linear ion crystals of arbitrary length are built in an automated fashion using transport waveforms and the scaling of dark lifetime with ion number for N <= 6 is investigated. These data are then used to consider the relevance of various loss channels.

Dans ce mémoire, nous proposons une méthodologie statistique permettant d’obtenir un estimateur de l’espérance de vie des clients en assurance. Les prédictions effectuées tiennent compte des caractéristiques individuelles des clients, notamment du fait qu’ils peuvent détenir différents types de produits d’assurance (automobile, résidentielle ou les deux). Trois approches sont comparées. La première approche est le modèle de Markov simple, qui suppose à la fois l’homogénéité et la stationnarité des probabilités de transition. L’autre modèle – qui a été implémenté par deux approches, soit une approche directe et une approche par simulations – tient compte de l’hétérogénéité des probabilités de transition, ce qui permet d’effectuer des prédictions qui évoluent avec les caractéristiques des individus dans le temps. Les probabilités de transition de ce modèle sont estimées par des régressions logistiques multinomiales. / In this master’s thesis, we develop a statistical method to estimate the lifetime expectancy of clients in the insurance domain. The forecasts are personnalized according to the clients’ own features, the most notable being the fact that they can have any combination of automobile and residential insurance products. Three approaches are compared. The first approach is the simple Markov model which assume homogeneity and stationnarity of the transition probabilities. The other model suggested – which is implemented both by direct computation and by simulation – allows for heterogeneity of the transition probabilities, thus providing forecasts which evolve in time along with the characteristics of the clients. The transitions probabilities are estimated using multinomial logistic regressions.

Le but de ce projet est d’étudier l’effet des défauts cristallins sur les propriétés optoélectroniques de photodétecteurs fabriqué à partir de « silicium noir », c’est-à-dire du silicium dopé et microstructuré par impulsions laser femtoseconde, ce qui lui donne une apparence noire mate caractéristique. Des échantillons de silicium noir ont été recuits puis implantés avec des ions ayant une énergie de 300 keV (Si+), 1500 keV (Si+) ou 2000 keV (H+). Trois fluences pour chaque énergie d’implantation ont été utilisées (1E11, 1E12, ou 1E13 ions/cm2) ce qui modifie le matériau en ajoutant des défauts cristallins à des profondeurs et concentrations variées. Neuf photodétecteurs ont été réalisés à partir de ces échantillons implantés, en plus d’un détecteur-contrôle (non-implanté). La courbe de courant-tension, la sensibilité spectrale et la réponse en fréquence ont été mesurées pour chaque détecteur afin de les comparer. Les détecteurs ont une relation de courant-tension presque ohmique, mais ceux implantés à plus haute fluence montrent une meilleure rectification. Les implantations ont eu pour effet, en général, d’augmenter la sensibilité des détecteurs. Par exemple, l’efficacité quantique externe passe de (0,069±0,001) % à 900 nm pour le détecteur-contrôle à (26,0±0,5) % pour le détecteur ayant reçu une fluence de 1E12 cm-2 d’ions de silicium de 1500 keV. Avec une tension appliquée de -0,50 V, la sensibilité est améliorée et certains détecteurs montrent un facteur de gain de photocourant supérieur à l’unité, ce qui implique un mécanisme de multiplication (avalanche ou photoconductivité). De même, la fréquence de coupure a été augmentée par l’implantation. Une technique purement optique a été mise à l’essai pour mesurer sans contacts la durée de vie effective des porteurs, dans le but d’observer une réduction de la durée de vie causée par les défauts. Utilisant le principe de la réflexion photo-induite résolue en fréquence, le montage n’a pas réuni toutes les conditions expérimentales nécessaires à la détection du signal. / The goal of this project is to study the effect of crystalline damage on the optoelectronic properties of photodetectors made from “black silicon” (i.e. femtosecond-laser microstructured silicon, which make it appear black). Black silicon samples were annealed then implanted with either 300 keV Si+, 1500 keV Si+ or 2000 keV H+ ions. The fluence used for the implantation was 1E11, 1E12 or 1E13 ion/cm2, resulting in nine different samples with a crystalline damage distribution of various depth and concentration. Photodetectors were fabricated on these samples, together with a control detector made from a non-implanted black silicon sample and then characterized. The I-V curves, spectral responsivities and frequency responses of the detectors were measured in short-circuit or under bias and compared. The detectors display an approximately ohmic behavior, but those implanted at a higher fluence show a slightly better current rectification. The implantation had a strong effect on the responsivity. The external quantum efficiency increased from (0.069 ± 0.001) % at 900 nm for the control detector up to (26.0 ± 0.5) % for the 1E12 cm-2, 1500 keV Si+ detector. With an applied bias of -0.50 V, the responsivity is increased and some detectors exhibit above unity photocurrent gain. Similarly, the cutoff frequencies of the implanted detectors are higher. A contactless experiment was attempted for the measurement of the effective carrier lifetime. The implantation damage was expected to reduce the carrier lifetime. The setup didn’t meet all experimental conditions required to detect the signal using frequency-domain photo-induced reflection.

In this master’s thesis the width of the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> meson is studied as a function of temperature. We consider a background medium consisting of a pion gas and assume a vanishing net baryon chemical potential. The width is obtained in the framework of large <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?N_%7Bc%7D" /> chiral perturbation theory and we consider terms up to next-to-leading order in the effective Lagrangian. We use a low-density approximation to calculate the width increase due to scattering with pions from the heat bath. The results suggest that the in-medium width for the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> may become of considerable size: at a temperature <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?T%5Capprox%2075" /> MeV we find a width increase of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5CDelta%5CGamma%5Capprox%203-4" /> MeV, comparable to the inverse lifetime of the fireball created in a heavy-ion collision. The <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> is of particular interested since it is intimately connected to the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?U(1)_%7BA%7D" /> anomaly of Quantum Chromodynamics (QCD). It has been speculated that <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?U(1)_%7BA%7D" /> may become a symmetry of QCD at high temperatures and studies of the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> could indicate if that is the case. Depending on for how large temperatures the results from large <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?N_%7Bc%7D" /> can be trusted, they indicate that the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Ceta'" /> may be possible to study experimentally in heavy-ion collisions due to its sizable in-medium width.

The main aim of this thesis paper is to determine the influence of physical and mechanical indices of asphalt concrete pavement on the operational properties of Lithuanian highway pavement as well as on the functional lifetime of road pavement. The analysis of pavement condition of Lithuanian highways is presented. The classification regarding the damage and deformation of material used for the construction of asphalt concrete pavement and of road pavement structure is provided. The causes of the afore-mentioned damages and deformations are also explained and rectification methods which can be applied to eliminate these causes are described. The operational conditions of the road pavement and its structure as well as the applicable methods are theoretically justified. In addition, the physical and mechanical indices of asphalt concrete pavement of the highway Vilnius – Kaunas - Klaipėda (A1) and of pavement roughness in accordance with IRI research data are given. The analysis of the data allowed the correlation between the two items to be determined. The research material was processed by means of the statistical software package “Statgraphics 5.1 Plius”. Standardized physical and mechanical indices of asphalt concrete pavement which affect the functional lifetime of pavement structure are presented. The conclusions and recommendations are provided.