<p>In the first part of the thesis, we have focused on providing a brief overview of Petname Systems starting from the introductory concept of Entity, Identity and Identity Management with a brief description on different IdM architectures. We have found that the Petname Model is well suited to be integrated in the Personal SP Identity model. We also provided a brief description on Identity Theft and the Phishing attack with different attack techniques and defense mechanisms. Then we summarized the history and evolution of the Petname Model in one place. Previously it was scattered among several web articles. We have formally defined the properties of Petname Systems and explained how this set of properties can satisfy the essential security usability principles. It is our belief that if these properties are followed in developing applications based on the Petname Model, it will improve the user experience and improve overall security by removing security vulnerabilities related to poor usability. The thesis has also analyzed two available Petname-based applications for server identification management and shown that they represent an improvement in usability, but unfortunately do not satisfy all the specified Security Usability principles. In the second part, we have developed the UniPet, a Petname Model based application with similar functionalities of the Petname Tool and the TrustBar, that utilizes the concept of aiding user in identifying SP identities securely on their side. We have deployed several technologies to meet the complex level of interaction the UniPet asks for. We have provided a brief discussion on each of the technologies to better understand the UniPet architecture. We have also shown that the UniPet has been a major improvement on GUI and on the security usability issues over those two applications. The UniPet satisfies all the properties of a Petname System and thus is fully compliant with the Security Usability principles. We believe that the UniPet will provide the users with an improved and secure browsing experience.</p>

<p>Session Initiation Protocol (SIP) has been used for signaling in many Voice over IP (VoIP) applications. Being more cost-effective than conventional circuit-switched systems, IP-based telecommunication systems are extensively employed by many service providers. As these systems gain more popularity, the need for dimensioning of such systems grows correspondingly. Moreover, accurate information about system capacity is necessary for future improvements of the system, as well as service provision and implementation planning. For these reasons, a solution supporting system performance evaluation is useful and beneficial in several ways. The goal of this research was to develop a performance evaluation framework for a SIP-based telecommunication system. The developed framework facilitates measurements of the maximum number of requests which can be processed by a system, and the amount of time required for call session establishment. With a user-friendly interface, the framework enables system testers to perform experiments using simulated SIP traffics, as well as to deal with results interpretation easily. In order to achieve the objective, studies of related technologies and available tools for SIP traffic generation have been carried out. Afterwards, the performance evaluation framework is designed and implemented. Lastly, the developed framework is used for evaluating the performance of EasyVPaBX, a SIP-based call handling system, in various system configurations. Keywords: SIP, Performance, Evaluation, Dimensioning, Measurement</p>

<p>With the continuous development of the Internet technologies new routing requirements have surfaced. In response, several adaptive, stochastic routing algorithms have been purposed. The Cross Entropy Ant System (CEAS) is an adaptive, robust and distributed routing and management system based on the swarm intelligence. Several prototype implementations and enhancements have been made on this system, however the level of TCP friendliness the CEAS may provide is yet an important issue. In order to investigate the level of TCP friendliness, the behavior of the CEAS system during different network dynamics needs to be understood. For this reason, the behavior of the CEAS system under different network event and its corresponding effects on TCP performance is examined first using a simple network. Later the level of TCP performance is measured on complex networks. Also the load sharing capabilities of the CEAS system is investigated the efficiency of the system to manage and update according to the network load. Additionally the results are compared against the results obtained from the standard Link State Routing protocol and the Distance Vector Routing protocol under similar conditions. In this work, we find that the update process in response to the change in network dynamics is slower on CEAS compared to the other systems. However, the update process speeds up with the increase in the ant rates. During such period the use of multiple path reduces the TCP performance. We also find that large amount of packets loop around some links during link failures. Such looping reduces the TCP performance significantly. However, implementing previous hop memory technique removes such loops and also help TCP resume transmission immediately after the link failure. Compare to the LSRP and the DVR, we find that CEAS manages network resources more efficiently to produce higher TCP performance. We find that the CEAS diverts the data traffic on the basis of the quality of the path rather than the length of the path. We also find that the CEAS system handles multiple TCP stream independently with equal priority. But the smaller transition delay on the ants compared to the data packet reduces the TCP performance to some extent. However, forcing the ants to experience longer queuing delay according to the traffic load improves the TCP performance as well as helps CEAS update more accurately.</p>

<p>Reducing grid harmonics and increasing grid stability are both major issues for the operation of rail vehicles. For stability investigation of complex power systems, simplified system models are in need in order to reduce the model complexity and the simulation time. In this thesis work the effect of modelling a voltage source converter (VSC) for traction power system with and without the detailed pulse width modulated (PWM)-switch model is modeled. Effect of different operating conditions for the switching model on the harmonic content of the system is also analyzed. The same disturbance is imposed for the two models and the low frequency oscillation of the DC- link voltage response is compared and analyzed. The effect of semiconductor switching on the stability limit of the system is also investigated. Furthermore, the performance of a PWM time delay compensation technique during transient is analyzed. The result shows that in the model including the switching the DC- link voltage oscillation is damped and has a better stability margin compared to the average model. In the detailed switching model a converter loss is included while in the average model a no loss ideal case scenario is considered. As far as the switching harmonic is considered, the switching model with an operational condition of a high switching frequency and a switching frequency with an integer multiple of the fundamental frequency has a low harmonic content on the system compared to the operating condition of a low switching frequency which is not integer multiple of the fundamental frequency. A unipolar voltage switching technique has also a tremendous advantage over the bipolar voltage switching technique as far as this harmonic content in the system is concerned. Using a unipolar voltage switching technique reduces the harmonic content in the overall railway system. For triangular carrier modulators, an average time delay from the reference voltage to the actuated PWM terminal voltage of half the switching frequency is assumed .The delay in DC- link voltage control loop caused by the switching dead-time effect was improved by compensation of dead-time in the inverse-park transformation block of the control loop. The comparison of the compensated and non-compensated model proves that the compensated model is better in terms of the overshoot of amplitude of transient.</p>

<p>In order to comply with governmentally announced greenhouse gas emission reductions goals and to consolidate an independent and stable electric power and energy supply, Norway must increase its installed renewable energy based power generation capacity. Profitability estimations, today’s available technical solutions and regulations concerning preservation of natural resources leave construction of new small hydro power plants behind as the most plausible alternative together with construction of wind farms. Global trends such as technologic development and progress and the public opinion indicate that future wind farms in Norway will be located offshore. The assumption is supported by the recent handing out of a concession to an offshore wind farm project for the first time in Norwegian history. The projects name is Havsul 1 and the licence involves construction of 350 MW offshore wind power. Havsul 1 will be located in Mid-Norway, which is the region in Norway where the Norwegian Transmission System Operator (TSO) Statnett is most concerned about their ability to execute their task of assuring safety of power supply in the future. The concern owes to lack of generation capacity and transmission constraints. Experience show that commissioning of large offshore wind farms will impose power balance associated challenges on the TSO. By applying a slightly modified model developed by Sintef of the Nordel synchronous system in the power simulation tool DIgSILENT PowerFactory, grid connection of 350 MW and 1000 MW offshore wind farms to a bus bar representing Mid-Norway were investigated, targeting reduction of frequency excursions. To execute the reduction task, a so-called centralised Load Frequency Control (LFC) scheme was implemented and four hydro power plants were designated to provide regulating power pursuant to a priority key that used their response times as input. To simulate power fluctuations in the time span of hours, real time wind data acquired from the Danish offshore wind farm Horns Rev 1 was used as input in the offshore wind farm model. These data were kindly provided by the Swedish power company Vattenfall. The power fluctuations simulations showed that LFC is a well-fitted tool for bridling frequency excursions in the Nordel synchronous system caused by fluctuating power generation in an offshore wind farm. During the power fluctuations, which were of a particularly challenging kind, the system frequency complied with Statnett’s normal operation requirements of 50 ±0.1 Hz. The results weren’t too surprising since LFC has been used successfully in Europe for many years. They did however show that the amounts of the so-called frequency controlled normal operation reserves in Nordel may need to be expanded in case of a massive expansion in wind power in Norway. Fault Ride Through (FRT) investigations were also conducted by introducing 3-phase short circuit faults at selected bus bars. The simulations showed that the FRT requirements in Norway were not violated even in the worst case simulations. Some choices regarding the setup of the model may have exalted the simulation results.</p>

<p>The work consists in developing a power conversion unit for solar panel connected to the grid. This unit will be a single phase inverter in the low power range (24/48 V - 100/200 W), with digital control and without a DC-DC stage. The final system should be suitable for laboratory work. This master project will be complete, starting with a detailed specification of the project and finishing with an experimental validation.</p>

<p>Password-based logon schemes have many security weaknesses. Smart card and biometric based authentication solutions are available as a replacement for standard password-based schemes for security sensitive environments. However, the cost of deployment and maintenance of these systems is quite high. On the other hand, mobile network operators have a huge base of deployed smart cards that can be reused to provide authentication in other areas significantly reducing costs. This master’s thesis presents a study of how the workstation identity management can be made more secure and user-friendly by using a mobile phone in the Windows workstation logon process. Two workstation logon schemes that utilize both the mobile phone and the UICC inside of the phone are proposed as a result of this study. The first scheme emulates a smart card reader and a smart card in order to interoperate with the Windows smart card framework to provide PKI-based logon. The mobile phone with the UICC card emulates a smart card that communicates with the emulated smart card reader via protected Bluetooth channel. The proposed scheme reuses the Windows smart card infrastructure as much as possible, both in terms of software and hardware. Therefore, a seamless integration with Active Directory and Window server is achieved. This scheme can work with any authentication scheme used with real smart cards. It can be used not only for the logon but also for all other functions typically done with smart cards (e.g. signing of documents, e-mails). In the second scheme, the mobile phone with the UICC serves as a token for generating OTP values based on a shared secret key and the time parameter. In order to design Windows logon architectures based on mobile phones, a study of relevant technologies, components, and their security aspects has been conducted.Existing phone-based authentication schemes have been thoroughly studied both from the usability and from the security points of view. This has been done to understand possible alternatives for different aspects of the architectures that were designed. The thesis analyzed how new authentication schemes in general and those that work with mobile phones in particular could be integrated into the Windows logon system. A conclusion is made that it is impossible to make a generic architecture that would easily support all existing and possible future mobile phone authentication schemes for the Windows logon. Windows is already a highly customizable environment and can support virtually any authentication scheme for the logon, though a considerable amount of modifications may be required to implement a particular scheme.</p>

<p>Characterization of Epoxy (diglycidyl ether of Bis-phenol A cured with Tri ethylene Tetra amine) without fillers was done. The Water absorption test at 95°C shows that at saturation the epoxy contains a water concentration of 2.089%. The diffusion coefficient of absorption is calculated as 0.021 cm2/s. The diffusion coefficient of desorption is calculated as 0.0987 cm2/s. The diffusion is almost 5 times faster than absorption. Also the material looses weight as the hydrothermal aging progresses. The water in the sample leads to chain scission which leads to the weight loss. The weight loss is more incase of absorption followed by desorption than only absorption. The chain scission leads to decrease in the mechanical strength by around 45%. The diffusion of water from the samples doesn’t affect the mechanical strength of the materials. The glass transition temperature reduces by 20°C with water inside the sample. The diffusion of water out of the sample only increases by around 10°C. The Dielectric response of the material shows that after the water absorption the sample shows high losses at lower frequencies. Also the increase in the real part of the permittivity increases with low frequency. The rapid increase in the real art of the permittivity of the material at lower frequencies can be attributed to a polarization at the electrode due both to accumulation of the charge carriers and to chain migrations. The breakdown test of the samples shows that with water in the sample the breakdown strength of the material decreases by 10 KV, but the material regains its dielectric strength when the water is diffused out. This shows that the chain scission and weight loss of the samples has no or minimum effect on the dielectric strength of the sample</p>

<p>This report is divided into six main chapters. It starts off with an introductory chapter explaining the different propulsion strategies that have been considered during the last semester, and the final propulsion system that has been decided upon. The final propulsion strategy has several demands when it comes to components that have to be implemented and what type of components they should be. The main purpose for me in this project was therefore to meet these demands. Main demands for me were to demonstrate different possibilities when it comes to controlling the lights in the PureChoice vehicle, and to make sure the vehicle had enough energy stored in alternative storage devices in order to have a fully functioning system when it comes to driving the vehicle and managing the safety system onboard. The report continues with five individual chapters explaining how these demands were solved and which components that have been considered and implemented in the final vehicle. All off the chapters start of with an introduction about the topic at hand. They then continue with an explanation about the different components used in the vehicle, and reasoning for why exactly these components were chosen. In order to determine how the components would function in the final propulsion system, laboratory tests were performed on all the involved parts, and these laboratory tests are described at the end of all the chapters. This report includes both theoretical calculations and practical solutions.</p>

<p>Summary Literatures on battery technologies and diagnosis of its parameters were studied. The innovative battery technologies from basic knowledge to world standard testing procedures were analysed and discussed in the report. The established battery test station and flowchart was followed during the battery test preparation and testing. In order to understand and verify the battery performance, the well established test procedures developed by USABC (United States Advanced Battery Consortium) and FreedomCAR were reviewed. Based on the standard battery test flow diagram, battery test procedures are mainly categorised as below; 1. Test plan and pre-test – readiness review 2. Core performance test – charging, discharging, power, capacity and other special tests 3. Life cycle/ageing test – accelerated ageing, calendar life, abuse and safety Commercial battery testers were used to carryout the core performance test but electrochemical impedance spectroscopy (EIS) was employed for life cycle test and also to investigate the state of health (SOH) and state of charge (SOC) of the battery. The standard test bench as shown below was used for the experiment under the scope of this thesis. Figure 1: Standard battery test station Study on impedance based modelling of battery and laboratory experiment to measure the impedance was carried out. Electrochemical impedance was measured by applying an AC potential to an electrochemical cell and measuring the current through the cell using the shunt in series where battery voltage was measured directly from the terminals as shown in figure 1.Commercially available battery sensors were used to measure the current, voltage and temperatures. Impedance was calculated internally and observed on computer through the battery test program and also observed on Nyquest plot where real part is plotted on the X-axis and imaginary part on Y-axis at one frequency. A typical impedance spectrum of a Li-ion battery tested in the laboratory at 250C is presented below. This figure shows the measured impedance for different state of charge (SOC) without dc excitation current. Figure 2: Impedance Spectra of a Li-ion battery At real impedance Re(Z)  42 m, the real axis intersection of the impedance spectra was observed in the figure 2. For lower frequencies, all spectra show two semicircles. The first semicircle is comparably small and slightly depressed, whereas the second one is larger, nearly non-depressed and grows remarkably with decreasing state of charge. Finally, at the low-frequency end of the depicted spectra, the diffusion impedance becomes visible. At high states of charge, the diffusion impedance shows a 45°-slope, which is typical of Warburg impedance (state of diffusion at certain frequency).</p>