Electrical production in Sweden today is mainly from nuclear and hydro power. However, there is large increase in renewable energy like wind power and the installed new capacity goals are large. Several electrical production sources are important for the sustainability of the energy system. Maintenance is an approach for keeping a system sustainable. The importance of structured maintenance for reliable electrical production systems triggers the development of qualitative and quantitative maintenance management methods. Examples of these methods are Reliability-Centered Maintenance (RCM) which is a structured qualitative approach that focuses on reliability when planning maintenance, and Reliability Centered Asset Management (RCAM) which is a development of RCM into a quantitative approach with the aim to relate preventive maintenance to total maintenance cost and system reliability. This thesis presents models, as applications of RCAM, based on the methods of Life Cycle Cost (LCC) and mathematical optimization, applied to wind and nuclear power plants. Both deterministic and stochastic approaches have been used and the proposed models are based on the Total Cost model, which summarizes costs for maintenance and production loss, and the Aircraft model, which is an opportunistic maintenance optimization model. Opportunistic maintenance is preventive maintenance performed at opportunities. The wind power applications in this study show on different ways to cover costs of condition monitoring systems (CMS) and further on economic benefits of these when uncertainties of times to failure are included in the model. The nuclear power applications show on that the optimization model is dependent on the discount rate and that a high discount rate gives more motivation for opportunistic replacements. When put into a stochastic framework and compared to other maintenance strategies it is shown that an extended opportunistic maintenance optimization model has a good overall performance, and that it, for high values of the constant cost of performing maintenance, is preferable to perform opportunistic maintenance. The proposed models, applied to wind and nuclear power plants, could be extended and adapted to fit other components and systems. / Reliability and cost centered maintenance methods

The usage of wireless communication has increased over the past few years. Most wired communications are replaced by wireless communication for ease of use. Wireless communication transfers confidential information like personal information and credentials between two entities. We can't probably say that it is safe to send this information via wireless communication. As more data is sent, more attacks happen to steal the data. Hence, it is necessary to implement secure methods to transfer the data between source and receiver. In this communication channel, we use secrecy capacity as a parameter to measure how data is sent securely between source and destination. Generally, to achieve high system performance, the information is sent with low power, but this reduces the signal efficiency at the receiver. So, in this thesis, we have implemented cooperative transmission to increase the efficiency of low power signals by adding the relays between source and destination. This thesis consists of two relays. The relay that obtains the maximum signal-to-noise ratio is selected for the primary communication link. The other relay sends the signal to the eavesdropper to confuse the eavesdropper. In this thesis, we have derived the mathematical expression for SNR at receiver eavesdropper, and also we have derived a word for outage probability and secrecy capacity. Then, we simulated the Matlab code to obtain results on how the secrecy capacity affects by changing the various parameters like path loss exponent and fading severity parameter and suggests which environment is better to maintain high secrecy capacity. We also analysed the system performance and secrecy capacity in the presence of eavesdropper as well.

Background: Microsporidia are obligate intracellular opportunistic fungi that cause significant pathology in immunocompromised hosts. However, 11 percent of immunocompetent individuals in the general population are microsporidia-seropositive, indicating that severe immune suppression may not be a prerequisite for infection. Encephalitozoon intestinalis is transmitted in contaminated water and initially infects gastro-intestinal enterocytes, leading to diarrheal disease. This organism can also disseminate to many other organs. A recent report suggests that microsporidia can establish persistent infections, which anti-fungal treatment does not eradicate. Like other intracellular pathogens, microsporidia infection stresses the host cell and infected individuals have elevated hydrogen peroxide and free radical levels. Findings. As oxidative stress can lead to DNA damage, we hypothesized that E. intestinalis-infection would increase host cell nuclear mutation rate. Embryo fibroblasts from Big Blue§ssup§TM§esup§ transgenic mice were E. intestinalis-infected and host nuclear mutation frequency was determined by selection of temperature-sensitive c-II gene mutant λ phage. The host mutation frequency in E. intestinalis-infected cultures was 2.5-fold higher than that observed in either mock-infected cells or cells infected with UV-inactivated E. intestinalis spores. Conclusions: These data provide the first evidence that microsporidia infection can directly increase host cellular mutation frequency. Additionally, some event in the microsporidia developmental cycle between host cell attachment and parasitophorous vacuole formation is required for the observed effect. As there is considerable evidence linking infection with other intracellular pathogens and cancer, future studies to dissect the mechanism by which E. intestinalis infection increases host mutation frequency are warranted.

Background: Microsporidia are obligate intracellular opportunistic fungi that cause significant pathology in immunocompromised hosts. However, 11 percent of immunocompetent individuals in the general population are microsporidia-seropositive, indicating that severe immune suppression may not be a prerequisite for infection. Encephalitozoon intestinalis is transmitted in contaminated water and initially infects gastro-intestinal enterocytes, leading to diarrheal disease. This organism can also disseminate to many other organs. A recent report suggests that microsporidia can establish persistent infections, which anti-fungal treatment does not eradicate. Like other intracellular pathogens, microsporidia infection stresses the host cell and infected individuals have elevated hydrogen peroxide and free radical levels. Findings. As oxidative stress can lead to DNA damage, we hypothesized that E. intestinalis-infection would increase host cell nuclear mutation rate. Embryo fibroblasts from Big Blue§ssup§TM§esup§ transgenic mice were E. intestinalis-infected and host nuclear mutation frequency was determined by selection of temperature-sensitive c-II gene mutant λ phage. The host mutation frequency in E. intestinalis-infected cultures was 2.5-fold higher than that observed in either mock-infected cells or cells infected with UV-inactivated E. intestinalis spores. Conclusions: These data provide the first evidence that microsporidia infection can directly increase host cellular mutation frequency. Additionally, some event in the microsporidia developmental cycle between host cell attachment and parasitophorous vacuole formation is required for the observed effect. As there is considerable evidence linking infection with other intracellular pathogens and cancer, future studies to dissect the mechanism by which E. intestinalis infection increases host mutation frequency are warranted.

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第19132号 / 情博第578号 / 新制||情||101(附属図書館) / 32083 / 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 高橋 達郎, 教授 原田 博司, 教授 梅野 健 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

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Ever since Marconi succeeded in his first demonstration on the possibility to communicate over the air overseas about a century ago, wireless communications have experienced dramatic improvements. Today's world sees the penetration of wireless communications into human life almost everywhere, from a simple remote control for TV to a cellular phone. With a better understanding of the adverse nature of the wireless propagation channels, engineers have been able to invent various clever techniques, i.e. Multiple Input Multiple Output (MIMO) technology, spread spectrum communications, Orthogonal Frequency Division Multiplexing (OFDM) to name a few, to achieve fast and reliable communications over each point-to-point link. Communications between multiple parties create networks. Limited Radio Frequency (RF) resources, e.g. transmit power, channel bandwidth, signaling time slots, etc., call for an optimal distribution of these resources among the users in the network. In this dissertation, two types of communication networks are of particular interest: cellular networks and mobile-relay-aided networks. For a symmetric cellular network, where a fixed communication infrastructure is assumed and each user has similar average Signal-to-Noise Ratio (SNR), we study the performance of a Maximum SNR (Max-SNR) scheduler, which schedules the strongest user for service, with the effects of channel estimation error, the Modulation and Coding Scheme (MCS), channel feedback delay, and Doppler shift all taken into account. The degradation of the throughput of a Max-SNR scheduler due to outdated channel knowledge for a system with large Doppler shift and asymmetric users is analyzed and mathematical derivations of the capacity of the system based upon an Auto-Regressive (AR) channel model are presented in the dissertation as well. Unlike the schedulers proposed in the literature, which instantaneously keep track of the strongest user, an optimal scheduler that operates on the properties of Doppler and the average SNR of each user is proposed. The high flexibility and easy deployment characteristics that Unmanned Aerial Vehicles (UAVs) possess endow them with the possibility to act as mobile relays to create secure and reliable communication links in severe environments. Unlike cellular communications, where the base stations are stationary, the mobility in a UAV-assisted network can be exploited to improve the quality of the communications. Herein, the deployment and optimal motion control problem for a mobile-relay-aided network is considered. A network protocol which achieves optimal throughput and maintains a certain Quality of Service (QoS) requirement is proposed from a cross-layer perspective. The handoff problem of the Access Point (AP) between various relays is studied and the effect of the mobility on the handoff algorithm is addressed.

This dissertation presents contributions to the fields of mobility modeling, wireless sensor networks (WSNs) with mobile sinks, and opportunistic communication in theme parks. The two main directions of our contributions are human mobility models and strategies for the mobile sink positioning and communication in wireless networks. The first direction of the dissertation is related to human mobility modeling. Modeling the movement of human subjects is important to improve the performance of wireless networks with human participants and the validation of such networks through simulations. The movements in areas such as theme parks follow specific patterns that are not taken into consideration by the general purpose mobility models. We develop two types of mobility models of theme park visitors. The first model represents the typical movement of visitors as they are visiting various attractions and landmarks of the park. The second model represents the movement of the visitors as they aim to evacuate the park after a natural or man-made disaster. The second direction focuses on the movement patterns of mobile sinks and their communication in responding to various events and incidents within the theme park. When an event occurs, the system needs to determine which mobile sink will respond to the event and its trajectory. The overall objective is to optimize the event coverage by minimizing the time needed for the chosen mobile sink to reach the incident area. We extend this work by considering the positioning problem of mobile sinks and preservation of the connected topology. We propose a new variant of p-center problem for optimal placement and communication of the mobile sinks. We provide a solution to this problem through collaborative event coverage of the WSNs with mobile sinks. Finally, we develop a network model with opportunistic communication for tracking the evacuation of theme park visitors during disasters. This model involves people with smartphones that store and carry messages. The mobile sinks are responsible for communicating with the smartphones and reaching out to the regions of the emergent events.

Rhodococcus equi is an important pathogen in foals between one to six months of age and is a major cause of death in in these animals. In addition, R. equi has recently emerged as a significant opportunistic pathogen in immunosuppressed humans, especially those infected with HIV. Despite the ability of the organism to survive stressful growth conditions, for example, exposure to elevated temperature and oxygen radicals, the role of heat shock proteins in the pathogenesis of R. equi has not been well documented. In this project we developed and optimised methods to purify the heat shock protein DnaK from R. equi, using a combination of ion-exchange and affinity chromatography. The effectiveness of the purification protocols were assessed using SDS-PAGE and Western-blotting with anti-DnaK antibodies, and the enzymic activity of the purified DnaK was verified with an ATPase assay. ATPase assays were also used to investigate the roles of other heat shock proteins in enhancing the activity of DnaK.

With the increasing demand for wireless communications, radio resource management (RRM) plays an important role in future wireless networks in order to provide higher data rates and better quality of services, given the limited amount of available radio resources. Although some specific features of wireless communication networks cause challenges to effective and efficient RRM, they bring opportunities that help improv- ing network performance and resource utilization. In this thesis, we focus on RRM issues related to the broadcast/multicast nature in wireless communication networks. The work is divided into two parts. In the first part, we exploit how to take advantage of the broadcast nature of wire- less transmissions in RRM by opportunistically applying two-way relaying (or network coding) and traditional one-way relaying. Different objectives are considered, includ- ing maximizing total packet transmission throughput (Chapter 2), minimizing costs related to transmission power and delay (Chapter 3), and minimizing packet transmis- sion delay subject to maximum and average transmission power limits (Chapter 4). While designing these scheduling schemes, the random traffic and channel conditions are also taken into consideration. Our results show that the proposed opportunis- tic scheduling schemes can indeed take good advantage of the broadcast feature at the relay nodes and achieve much higher throughput and, in some scenarios, provide close-to-optimum QoS performance. The second part (Chapter 5) of the thesis deals with the issue of efficient resource management in multicast communications, where we study channel sharing and power allocations for multicast device-to-divice (D2D) communication groups underlaying a cellular network. In such a scenario, D2D multicasting together with the mutual inter- ference between cellular and D2D communications, makes the interference conditions and power allocations a very complicated issue. Different approaches are proposed that allow each D2D group to share the cellular channels and allocate transmission power to each D2D and cellular transmitter, so that the sum throughput of D2D and cellular users is maximized. Our results indicate that it is possible to achieve close-to-optimum throughput performance in such a network. / Dissertation / Doctor of Philosophy (PhD)